ill 


n  (.'"    '  VP 

-V  IV  I.    i.  , 


INTERNATIONAL   CHEMICAL   SERIES 
H.  P.  TALBOT,  PH.D.,  CONSULTING  EDITOR 


THE  ANALYiSIS 

OF 

FUEL,  GAS,  WATER  AND  LUBRICANTS 


PUBLISHERS     OF     BOOKS      F  O  R^. 

Coal  Age     *     Electric  Railway  Journal 

Electrical  World  v  Engineering  News-Record 

American  Machini  st  vlngenieria  Internacional 

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Chemical,  6   MetallurgicallEngineering 

Electrical  Merchandising 


THE  ANALYSIS 

OF 

FUEL,  GAS,  WATER  AND  LUBRICANTS 


BY 
S.  W.  PARR 

PROFESSOR   OF   APPLIED   CHEMISTRY,    UNIVERSITY   OF   ILLINOIS 


THIRD  EDITION 


MCGRAW-HILL  BOOK  COMPANY,  INC. 

NEW  YORK:  370  SEVENTH  AVENUE 

LONDON:  6  &  8  BOUVERIE  ST.,  E.  C.  4 

1922 


P3 

I       2-i_ 


COPYRIGHT,  1922,  BY  THE 
McGRAW-HiLL  BOOK  COMPANY,  INC. 


COPYRIGHT,  1911,  1916,  BY  S.  W.  PARR 


THK     MAFIAS     PRXiSS     T  O  K  K     PA 


PREFACE  TO  THIRD  EDITION 

The  present  edition  has  been  expanded  somewhat  to  admit 
of  its  being  used  as  a  text  by  students  in  Chemistry  and  Chemical 
Engineering  in  their  Junior  year.  It  is  believed  that  the  added 
material  will  still  leave  the  work  well  adapted  to  the  chemical 
status  of  students  in  Mechanical  Engineering.  For  such  students 
it  is  well  to  begin  with  the  topic  of  Boiler  Waters,  since  this 
serves  as  an  excellent  medium  for  reviving  their  elementary 
chemistry.  For  such  students  it  will  be  found  desirable  also  to 
devote  two  or  three  periods  to  a  review  of  such  topics  as  no- 
menclature, especially  that  relating  to  acids,  bases  and  salts,  also 
valence,  reactions,  solubilities,  and  a  simplified  arrangement  of 
the  periodic  table  which  will  set  forth  these  properties  for  about 
16  or  18  of  the  more  common  elements.  This  will  include  prac- 
tically all  of  the  chemical  considerations  likely  to  be  met  with  in 
the  study  of  boiler  waters.  It  will  have  the  further  advantage  of 
connecting  many  chemical  facts  with  a  topic  of  immediate  interest 
to  the  engineer,  and  in  such  a  manner  as  incidentally  to  advance 
him  materially  in  the  matter  of  his  chemical  information. 

The  author  is  under  special  obligation  to  Floyd  B.  Hobart  for 
his  very  efficient  help  in  preparing  the  manuscript  for  the  printer. 
He  wishes  also  to  express  his  appreciation  for  helpful  suggestions 
and  careful  reading  of  the  text  by  Dr.  T.  E.  Layng  and  Dr.  M.  J. 
Bradley,  also  to  Dr.  R.  E.  Greenfield  for  reviewing  the  text  on 
Boiler  Waters  and  to  J.  M.  Lindgren  for  helpful  suggestions  on 
methods  for  fuels  and  oils. 

Criticisms   and   suggestions   from   users   will   be   especially 
welcome. 

S.  W.  PARR. 

UNIVERSITY  OF  ILLINOIS, 
URBANA,  ILLINOIS, 
October,  1921. 

494208 


PREFACE  TO  FIRST  AND  SECOND  EDITIONS 

This  work  is  intended  primarily  for  Juniors  in  Mechanical  and 
Railway  Mechanical  Engineering  at  the  University  of  Illinois. 
From  the  chemical  standpoint,  it  is  a  very  serious  problem  to 
know  what  may  profitably  be  attempted  in  the  way  of  analytical 
methods  in  the  case  of  students  whose  chemical  experience  is 
meager.  But,  however  unsatisfactory  the  amount  of  preliminary 
training,  it  is  obvious  that  the  curriculum  in  Engineering 
courses  is  already  overcrowded,  hence  the  obtaining  of  a  better 
prerequisite  in  chemistry  is  well  nigh  impossible.  The  work  as 
herein  outlined  is  the  result  of  ten  years  of  effort  to  make  the 
most  of  the  situation.  It  would  be  quite  too  much  to  claim  that 
in  the  evolution  of  the  work  a  satisfactory  status  has  been 
attained.  It  is  hoped,  however,  that  the  course  will  at  least 
help  the  engineer  to  a  better  understanding  of  the  literature  of 
the  topics  considered  and  also  to  an  appreciation  and,  conse- 
quently, a  more  intelligent  use  of  data  which  may  come  into  his 
hands  from  the  chemist.  It  may  not  be  out  of  place  to  state 
further  that  the  course,  which,  at  the  first,  was  inaugurated  with 
no  little  misgiving,  has  more  than  justified  the  experiment.  For 
this  result  credit  is  due  the  students,  who,  from  year  to  year  have 
carried  the  work  through  with  a  responsiveness  which  has  been 
the  main  stimulus  in  developing  this  outline  into  its  present  form. 

Part  I  is  a  synopsis  only  of  the  lectures  given.  Part  II  consists 
essentially  of  laboratory  directions  for  the  analytical  methods 
there  undertaken.  The  time  allowance  for  lectures,  quizzes, 
and  laboratory  is  nine  hours  per  week  for  18  weeks.  The  amount 
of  work  as  outlined  is  such  that  the  average  student  covers  the 
ground  in  the  time  prescribed. 

Special  acknowledgment  is  due  Dr.  H.  J.  Broderson  for  sug- 
gested improvements  in  the  present  edition  and  for  valued  assist- 
ance in  the  reading  of  proof. 


CONTENTS 

PAGE 
PREFACE  TO  THIRD  EDITION v 

PREFACE  TO  FIRST  AND  SECOND  EDITIONS vii 

PART  I 

LECTURES 
CHAPTER  I 

FUELS - 1 

Introduction — Fuel  types — Coal — Coke — Wood — Petroleum — 
Distillates — Alcohol — Gases. 

CHAPTER  II 

COAL : 5 

Introduction — Output — Distribution  of  reserve  supplies — Relative 
output  of  principal  producing  states — Distribution  of  types. 

CHAPTER  III 

SAMPLING  OF  COAL 11 

Introduction — Necessity  of  care — Material  to  be  taken — Amount 
— Ratio  of  size  to  mass — Mixing  and  subdividing — Riffling 
— Sampling  a  carload — Composite  samples — Mechanical  sampling 
— Moisture  control — Dust  determinations — Laboratory  sample. 

CHAPTER  IV 

ANALYSIS  OF  COAL 25 

Moisture  and  nomenclature — Calculations — Methods  of  analysis — 
General  plan — Interpretation  of  moisture  values — Ash — Sulphur — 
Volatile  matter — Fixed  carbon. 

CHAPTER  V 

UNIT  COAL : 31 

Definitions — Derivation  of  the  formula  for  unit  coal — Correction 
constant  for  water  of  composition — Accuracy  of  constants  em- 
ployed for  correction  of  ash. 

ix 


x  CONTENTS 

PAGE 

CHAPTER  VI 

CALORIMETRIC  MEASUREMENTS. 36 

Definitions — Heat  values  by  calculation — The  Berthier  test — 
Lewis  Thompson  calorimeter — Other  types — Oxygen  bomb  calori- 
meter— Correction  for  radiation — Adiabatic  insulation — Correc- 
tion for  acids — Correction  for  fuse  wire — The  peroxide  calorimeter 
— Gross  and  net  heat  values. 

CHAPTER  VII 

ULTIMATE  ANALYSIS 49 

Total  carbon — Derivation  of  hydrogen  by  calculation. 

CHAPTER  VIII 

CLASSIFICATION  OF  COALS 51 

Frazer's  classification — Fuel  ratio — Carbon-hydrogen  ratio — 
Carbon  ratio — Classification  by  heat  values — Derivation  of  heat 
values  for  unit  coal — Composition  of  Illinois  coals. 

CHAPTER  IX 

COAL  CONTRACTS 59 

Introduction — Calculation  of  commercial  heat  values  for  contract- 
ing purposes — Significance  of  heat  values — Concerning  the  ash — 
Bids  and  awards — Price  and  payment — The  formulation  of  propo- 
sals. 

CHAPTER  X 

THE  COMBUSTION  OF  COAL 65 

General  principles — Oxygen  supply — Smoke — Clinker  formation- 
Fusibility  of  ash — The  wetting  of  coal. 

CHAPTER  XI 

STORAGE,  WEATHERING  AND  SPONTANEOUS  COMBUSTION 73 

Deterioration — Spontaneous  combustion — Storage  methods. 

CHAPTER  XII 

COKE 80 

General  statement — Metallurgical  coke — Sampling  and  analysis — 
Pulverizing  of  coke — Volatile  matter — Sulphur. 

CHAPTER  XIII 

WOOD 83 

Introduction — Heat  values. 

CHAPTER  XIV 

PETROLEUM,  DISTILLATES  AND  ALCOHOL 85 

Use — Output — Heat  values — Distillates — Alcohol. 


CONTENTS  xi 

PAGE 

CHAPTER  XV 

FUEL  GAS 89 

Types — Heating  value  of  gas — Flow  calorimeters — High  and  low 
heat  values  for  combustible  gases — Ammonia  and  Sulphur — Ap- 
paratus for  the  analysis  of  fuel  gases — Analysis  of  fuel  gas — Com- 
putation of  volume  of  paraffins  from  analytical  data — Heat  values 
by  calculation. 

CHAPTER  XVI 

FLUE  GASES 104 

Gas  volumes — Sampling  and  analysis — Calculation  of  efficiencies 
and  heat  losses — Other  losses. 

CHAPTER  XVII 

BOILER  WATERS,  THEIR  EXAMINATION,  CHARACTER  AND  TREATMENT  .  112 
Water  analysis — Source  of  mineral  constituents — Chemical 
characteristics  of  the  mineral  constituents — Solubility  of  Gypsum 
— Effects  of  Impurities — Scaling  Ingredients— Effect  of  scale — 
Foaming  ingredients — Corrosive  ingredients — Classification — 
The  chemical  treatment  of  boiler  waters — Treatment  with  lime — 
Treatment  with  soda  ash — Treatment  with  coagulants — Indus- 
trial methods — Summary  of  ratios — Standards  for  indicating 
degrees  of  hardness — Limits  of  purification — Typical  waters  and 
their  treatment — Zeolites. 

CHAPTER  XVIII 

LUBRICANTS 137 

Introduction — Animal  and  vegetable  oils — Mineral  oils — Com- 
pounded oils — Testing. 

PART  II 

LABORATORY  METHODS 

CHAPTER  XIX 

THE  PROXIMATE  ANALYSIS  OP  COAL 141 

Introduction — The  laboratory  sample — Moisture  loss  on  air  drying 
— Working  sample — Moisture  in  the  laboratory  sample — Total 
moisture — Ash — Volatile  matter,  official  method — Volatile  matter, 
porcelain  crucible  method — Fixed  carbon — Calculations. 

CHAPTER  XX 

CALORIMETRY,  USING  SODIUM  PEROXIDE 149 

General   statement — The   fuel   sample — The    chemical:   sodium 
peroxide — The  accelerator:  potassium  chlorate — Making  up  the 
charge — Ignition — Temperature  readings — Calculations — To  dis- 
mantle— Anthracites  and  coke — For  petroleum  oils — Gasoline,  etc. 
— Standardiz  ation. 


xii  CONTENTS 

PAGE 

CHAPTER  XXI 

CALORIMETRY,  USING  THE  OXYGEN  BOMB 161 

General  statement — Heat  values  by  oxygen  bomb  calorimeter — 
Corrections — Standardization — Adiabatic  Conditions. 

CHAPTER  XXII 

SULPHUR  DETERMINATIONS 171 

General  Statement — Total  Sulphur. 

CHAPTER  XXIII 

ULTIMATE  ANALYSIS 179 

Total  carbon  determination — Hydrogen — Oxygen. 

CHAPTER  XXIV 

FUEL  GASES  ANALYSIS 185 

Introduction — Description  of  apparatus — Manipulation  and 
description  of  reagents — Determination  of  sulphur  in  gas — Direct 
determination  of  heating  value — Operation  at  the  Junker  calori- 
meter. 

CHAPTER  XXV 

THE  ANALYSIS  OF  FLUE  GASES 201 

Reagents — The  analysis  of  atmospheric  air — The  analyst  of 
respired  air — Flue  gas. 

CHAPTER  XXVI 

ANALYSIS  OP  BOILER  WATERS 204 

Normal  solutions — Standard  sodium  carbonate — Standard  sulfuric 
acid — Determination  of  sulphur — Standard  calcium  chloride  and 
soap  solutions — Standardization  of  the  soap  solution — Determina- 
tion of  calcium  sulphate  in  water — Excess  of  tree  carbon  dioxide — 
Total  alkalinity  and  temporary  hardness — Magnesia — Permanent 
hardness — Negative  hardness — Total  hardness — Determination 
of  total  sulphates — Determination  of  total  chlorides — Total  alkalies 
— Examination  of  a  treated  water — Summary  of  results  and  calcu- 
lations. 

CHAPTER  XXVII 

OIL  EXAMINATION 221 

Specific  gravity — Flash  and  fire  test — Viscosity — Free  acid — 
Saponification  number — Maumene"  test — The  Conradson  test 
— Emulsification. 

APPENDIX 230 

INDEX  .  .  245 


THE  ANALYSIS 

OF 

FUEL,  GAS,  WATER  AND  LUBRICANTS 

PART  I 
LECTURES 

CHAPTER  I 

FUELS 

Introduction. — Motion,  industrially  considered,  is  a  commodity 
which,  when  available  in  proper  form  and  in  sufficient  quantity,  is 
designated  as  power. 

The  sources  of  motion  are  two  in  number  : 

1.  Gravity. 

2.  Chemical  action. 

Gravity  is  transformed  into  motion  through  the  medium  of 
falling  water,  and  to  a  smaller  extent  by  means  of  wind  currents. 

Chemical  activity  may  be  derived  from  the  world's  fuel  supply 
in  greater  amount  and  at  less  cost  than  from  any  other  source. 

By  the  burning  of  fuel,  chemical  action  may  be  made  to  transfer 
its  motion  through  the  medium  of  steam  or,  to  a  smaller  extent, 
as  in  the  internal  combustion  engine,  directly  and  without  any 
medium,  to  the  working  parts  of  machinery.  Proximity  to  fuel 
beds,  therefore,  or  accessibility  by  reason  of  shipping  facilities 
is  an  index  of  present  or  potential  activity  along  industrial  lines. 
Hence,  it  is  evident  that  the  fundamental  purpose  of  the  indus- 
trial examination  of  fuels  is  to  measure  correctly  the  amount 
of  chemically  active  material  which  resides  in  a  given  sample. 
This  may  be  determined  in  two  ways :  First,  by  analytical  meth- 
ods wherein  the  amount  of  inorganic  or  chemically  inactive 

1 


LUBRICATION 


substance  is  determined,  as  distinct  from  the  organic  or  chem- 
ically active  material;  and,  second,  by  actual  combustion 
whereby  the  fuel  is  made  to  indicate  its  activity  by  the  evolution 
of  heat,  the  quantity  of  which  may  be  measured. 

Fuel  Types.  —  For  convenience  in  discussion,  fuels  are  divided 
into  solid,  liquid,  and  gaseous  types.  This  classification  with 
further  subdivisions  may  be  shown  in  tabulated  form  as  follows  : 

[Coal 

Solid       <  Coke  and  Charcoal 
I  Wood 

Petroleum 

Liquid        Distillates 
Alcohol 
Natural  Gas 
Gaseous     House   Gas 
Producer  Gas 

Coal.  —  Coal  is  by  far  the  most  abundant  and  cheapest  of  all 
fuels.  It  varies  in  character  from  the  hard,  rock-like  anthracites 
to  the  soft  lignites.  The  inert  non-active  substances  in  the  form 
of  water  and  ash  vary  from  8  to  40  per  cent,  and  are  inversely 
related  to  the  quantity  of  heat  available.  Since  these  factors 
are  fundamental  in  the  commercial  estimation  of  values,  classi- 
fication, etc.,  they  will  be  discussed  under  the  more  general 
treatment  of  coal  which  is  taken  up  later. 

Coke.  —  Coke  is  at  present  chiefly  a  fuel  having  special  proper- 
ties which  make  it  suitable  for  metallurgical  purposes.  It  has 
very  little  inactive  material  except  the  ash,  which  is  always  of 
higher  percentage  than  in  the  coal  from  which  it  is  made.  Meas- 
ured in  terms  of  heat  units,  coke  is  approximately  equal  to  the 
average  anthracite  coal. 

Wood.—  By  reason  of  the  high  cost  of  wood,  it  is  rapidly 
passing  out  of  the  list  of  available  fuels.  While  its  content  of 
inactive  substance  in  the  form  of  ash  is  low,  its  content  of  free 
moisture  is  high  even  in  seasoned  wood,  and  together  with 
combined  water  constitutes  more  than  half  of  the  wood  by  weight. 
Its  activity,  therefore,  measured  as  heat  is  only  about  half  that 
of  good  coal  averaging  6,500  or  7,000  B.t.u.  per  pound  of  wood. 
Since  a  cord  of  well  seasoned  oak  or  maple  weighs  approximately 
4,000  lb.,  that  amount  is  equal  in  heat  value  to  1  ton  of  coal. 


FUELS  3 

Pine  wood  is  approximately  \  as  heavy  with  a  slightly  higher 
thermal  value  per  pound. 

Petroleum. — Chemically  considered,  petroleum  is  a  complex 
mixture  of  hydrocarbons  in  which  those  of  the  heavier  type, 
having  a  lower  ratio  of  hydrogen  to  carbon,  predominate.  The 
heat  values  range  from  18,000  to  20,000  B.t.u.  per  pound.  Crude 
petroleum  varies  in  character,  some  districts  yielding  heavier 
and  some  lighter  oils.  Petroleum  residues  have  had  the  lighter 
oils  removed  by  distillation.  These  residues  are  of  higher 
specific  gravity  and  lower  heat  value. 

Distillates. — The  distillates  are  hydrocarbon  compounds 
mainly  derived  from  petroleum,  and  are  almost  entirely  free 
from  inactive  material.  Their  heat  value  varies  with  the  specific 
gravity,  which  directly  is  a  measure  of  the  ratio  of  carbon  to 
hydrogen.  The  lighter  the  distillate  the  higher  the  ratio  of 
hydrogen  and,  consequently,  the  higher  the  heat  value,  which 
may  vary  from  19,000  to  22,000  B.t.u.  per  pound. 

Alcohol. — Alcohol  is  a  prospective  rather  than  a  present  source 
of  fuel  energy.  It  involves  the  fermentation  of  starch  as 
obtained  from  grain,  potatoes,  etc.  or  of  sugars,  as  in  by-product 
molasses  from  sugar  factories,  or  of  wood  waste  after  hydrolyzing 
the  cellulose.  Interesting  possibilities  also  of  synthetic  alcohol 
from  acetylene  and  ethylene  have  recently  been  developed. 

Alcohol  has  no  ash  but  a  large  percentage  (34.8  per  cent)  of 
combined  oxygen,  which  approximately  represents  the  inert 
material.  Its  heat  value  in  pure  form  is  12,391  B.t.u.  per  pound. 

One  important  feature  connected  with  alcohol  is  the  fact 
that  while  other  sources  of  volatile  fuels  present  a  limited  or 
diminishing  supply,  the  possible  expansion  of  material  for  the 
production  of  alcohol  is  unlimited. 

Gases. — Gases  are  more  or  less  mixed  with  inert  material  and, 
when  measured  with  reference  to  their  chemical  activity  in  the 
form  of  heat,  the  values  are  referred  to  a  cubic  foot  at  60°F. 
temperature  and  a  pressure  of  30  in.  of  mercury,  as  representing 
the  average  or  standard  temperature  and  pressure  of  the  atmos- 
phere. Because  of  the  inevitable  tendency  for  all  forms  of  this 
material  to  have  an  admixture  of  inert  gases,  the  heat  values  are 
very  variable.  Their  character  may,  however,  be  expressed  in  a 
general  way  as  follows: 


4  FUEL,  GAS,  WATER  AND  LUBRICATION 

Natural  gas  is  usually  composed  in  large  part  of  methane  or 
marsh  gas,  which  in  pure  form  has  a  value  of  1,010  B.t.u.  per 
cubic  foot  at  the  above  temperature  and  pressure. 

House  gas  in  the  majority  of  cities  in  the  United  States  is 
required  to  have  a  heat  value  of  approximately  600  B.t.u.  per 
cubic  foot.  This  standard,  however,  is  being  lowered  in  many 
localities. 

Producer  gas  may  vary  from  150  to  225  units  in  the  richer  form 
to  125  units  in  the  "suction"  gas  producer,  and  to  as  low  as  90 
units  per  cubic  foot  in  the  gases  from  the  blast  furnace,  which 
may  be  looked  upon  as  a  special  type  of  gas  producer. 


CHAPTER  II 
COAL 

Introduction. — Of  all  the  fuel  supplies  available,  coal  consti- 
tutes by  far  the  largest  part.  Our  chief  consideration,  there- 
fore, will  be  given  to  this  topic.  A  glance  at  the  map, 
Fig.  1,  will  give  a  general  idea  of  the  distribution  of  coal  in  the 
United  States.  These  coal  areas  together  with  transportation 
facilities  are  the  chief  factors  in  the  development  of  industrial 


FIG.  1. — Distribution  of  coal  fields  in  the  United  States. 

centers.  From  the  economic  standpoint  we  will  be  interested 
in  the  output  as  a  whole  and  also  the  relative  yields  from  the 
main  producing  areas.  The  types  also  and  their  distribution 
are  of  chemical  as  well  as  industrial  importance  and  are  given 
brief  reference. 

Output. — The  annual  output  of  coal,  including  lignites,  in 
the  United  States  for  1920  was  approximately  676,000,000  short 
tons.  A  chart,  Fig.  2,  of  the  production  by  years  is  of  interest 
since  it  serves  as  an  index  of  industrial  activity.  It  presents  also 
a  suggestion  in  graphic  form  of  the  possibility  of  ultimate 

5 


6 


FUEL,  GAS,  WATER  AND  LUBRICATION 


exhaustion  of  this  source  of  fuel  supply,  and  the  necessity  of 
developing  the  highest   possible   efficiencies  in  its  use.     Inci- 


1865        I89O         I69S         I9OO        I9O5         I9/O         /9/S         /92O 

FIG.  2. — Annual  output  of  coal  in  the  United  States,  1880  to  1920. 


FIG.   3. — Coal  reserves,   showing  the  relative   available   coal  resources  of  the 

United  States.1 

dentally,  it  may  be  noted  that  the  world  output  of  coal  for  1920 
was  estimated  at  1,430,000,000  short  tons,  from  which  it  will  be 
1  111.  State  Geol.  Surv.  Yearbook  for  1916,  p.  26. 


COAL 


seen  that  the  yield  for  the  United  States  was  45  per  cent  of  the 
total. 

Distribution  of  Reserve  Supplies. — A  chart  of  the  coal  resources 
by  states  is  shown  in  Fig.  3.  The  estimated  tonnage  in 
reserve  for  the  five  states  having  the  most  extensive  coal  deposits 


COLO 


ILL. 


N.YA. 


PENH, 


OHIO. 


193.060.318.000 


181.280.129.000 


137.063.282.000 


98.286.522.000 


84.344.704.000 


FIG.  4. — Available  bituminous  coal,  short  tons.1 

is  shown  by  comparative  areas  in  Fig.  4.  From  this  chart  it 
will  be  seen  that  Colorado  has  the  greatest  amount.  Very  con- 
siderable areas,  however,  are  at  so  great  a  depth  that  the  winning 
of  all  the  coal  reserve  of  that  state  is  somewhat  problematical. 
Large  deposits  also  are  of  the  subbituminous  or  lignitic  type, 

1  111.  State  Geol.  Survey. 


8 


FUEL,  GAS,  WATER  AND  LUBRICATION 


hence  supremacy  in  the  matter  of  fuel  values  is  not  likely  to 
migrate  westward. 

Relative  Output  of  Principal  Producing  States. — The  relative 
production  of  bituminous  coal  for  the  four  principal  producing 
states  is  shown  in  Fig.  5.  While  the  coal  resources  of  Illinois 
exceed  those  of  either  Pennsylvania  or  West  Virginia,  the  annual 
production  for  these  states  is  not  in  relative  proportion  to  the 
estimated  reserves.  The  explanation  would  doubtless  be  found 
mainly  in  the  matter  of  chemical  composition  and  special 
characteristics.  For  example,  by  far  the  greater  part  of  the 


PRODUCTION      BITUMINOUS      COAL      1920 

CALENDAR  YEAR 
_Q__  50  100  ISO 2QQ MILLIONS 


FlG.    5. — Bituminous  coal  output. 

coking  coals  are  mined  in  Pennsylvania.  In  1920  the  estimated 
amount  of  coal  devoted  to  coke  making  was  77,000,000  tons.  If 
the  coals  of  Illinois  were  able  to  produce  a  metallurgical  coke 
and  Pennsylvania  coals  were  not  so  constituted,  other  factors 
remaining  the  same  it  would  doubtless  result  in  an  interchange 
of  data,  that  is,  Illinois  would  be  credited  with  an  output  of 
163,000,000  tons  and  Pennsylvania  with  90,000,000  tons.  These 
figures  would  then  more  nearly  conform  to  the  relative  reserves 
for  each  state.  This  reference  alone,  among  numerous  others 
which  might  be  given,  may  serve  as  an  illustration  of  the  desira- 
bility on  the  part  of  the  chemist  of  familiarizing  himself  with  the 


COAL 


9 


composition,  characteristics  and  types  of  the  coals  in  the  various 
regions  of  the  country.  Greater  efficiency  in  the  use  of  a  low- 
grade  coal  may  even  give  it  an  advantage  over  the  coal  of  higher 
grade.  Coking  conditions  may  also  be  modified  so  that  the 
chemical  studies  connected  with  our  coal  supplies  may  involve  a 
wide  range  of  interests  from  the  purely  scientific  phase  to  the 
relations  which  are  mainly  industrial  or  economic. 


IMA*,. 

Y-- 


CUM  i  NOUS 


FIG.    6. — Eastern  coal  fields. 

Distribution  of  Types. — It  is  not  intended  at  this  point  to  take 
up  the  topic  of  coal  classification  in  detail.  It  should  be  noted, 
however,  that  certain  geological  conditions  have  brought  about 
chemical  changes  in  the  coal  beds  which  have  resulted  in  a  pro- 
gression westward  of  certain  type  characteristics  such  as  the 
content  of  volatile  matter  or  the  amount  of  free  moisture  retained 
in  the  coal  seam.  For  example,  by  reference  to  Fig.  6,  the 
numbers  1  to  3  inclusive  show  the  location  of  the  coals  having 
the  lowest  volatile  matter,  the  anthracites.  Coals  numbered 


10  FUEL,  GAS,  WATER  AND  LUBRICATION 

5  to  10  are  of  the  bituminous  type  but  low  in  volatile  matter, 
while  in  the  next  zone  westward  are  found  the  high-volatile 
bituminous  coals.  Further  west,  as  in  Indiana  and  Illinois, 
other  zonal  characteristics  of  a  chemical  nature  occur  which  will 
be  better  understood  when  the  topic  of  classification  is  discussed. 


CHAPTER  III 
SAMPLING  OF  CoAL1 

Introduction. — Samples  may  be  taken  by  different  methods  and 
for  a  variety  of  purposes.     Three  kinds  are  generally  recognized : 

1.  Hand  samples. 

2.  Face  samples. 

3.  Commercial  samples. 

1.  Hand  Samples. — As  the  name  implies,  hand  samples  are 
taken  in  small  amounts  and  the  entire  sample  is  submitted  for 
inspection  and  analysis.     In  the  nature  of  the  case  such  samples 
are  selected  and  are  not  representative  of  the  mass  from  which 
they  come.     Their  analysis  may  be  of  interest  to  the  person 
collecting  them  but  the  results  are  without  commercial  value  or 
significance. 

2.  Face  Samples. — This  term  is  applied  to  samples  taken  at  the 
working  face  of  a  coal  seam.     They  are  essential  for  purposes  of 
scientific  study  and  serve  as  a  basis  for  determining  the  changes 
that  occur  in  the  process  of  mining,  transportation  and  storage. 
The  taking  of  such  samples  is  not  different  in  principle  from  the 
taking  of  commercial  samples.     The  chief  essential  is  a  kit  of  the 
knock-down  type,  not  too  heavy  for  packing  and  not  too  tedious 
in  setting  up  and  operating.     Specific  details  are  not  given  here. 

3.  Commercial  Samples. — The  majority  of  samples  are  taken 
in  connection  with  industrial  operations,  in  the  process  of  coal 
inspection,   control  of  contracts,   determination  of  efficiencies, 
etc.,  and  involves  the  sampling  of  wagon  loads,  car  lots,  barge 
shipments  and  masses  in  storage.     The  general  principles  under 
any  of  these  conditions  are  the  same.     The  important  features 
to  be  observed  are  given  special  emphasis  as  follows : 

Necessity  of  Care. — Without  question,  the  critical  point  in  the 
entire  range  of  coal  inspection  and  analysis  is  in  the  sampling. 

1  Adapted  from  111.   State  Geol.   Surv.,  Bull.    29,    Purchase  and  sale  of 
Illinois  coal  on  specification,  by  S.  W.  PARR  (1914). 

11 


12  FUEL,  GAS,  WATER  AND  LUBRICATION 

If  the  sample  taken  is  truly  representative  of  the  entire  lot,  the 
results,  if  accurate  in  themselves,  furnish  correct  information  as 
to  the  larger  mass  of  which  the  sample  is  a  part.  If,  on  the  other 
hand,  the  sample  is  in  error,  the  results  of  the  analysis  though 
correct  in  themselves  will  be  in  error  so  far  as  they  relate  to  the 
mass  under  consideration.  Throughout  the  process  of  sampling 
two  points  must  be  observed  with  scrupulous  care : 

First. — The  sample  taken  must  be  representative  of  the  whole, 
that  is,  the  distribution  of  the  various  substances  which  go  to 
make  up  the  original  mass  must  be  maintained  without  any 
change  in  the  relative  amount  of  the  various  constituents. 

Second. — The  moisture  content,  which  changes  readily,  must 
be  under  exact  control  so  that  at  any  stage  the  ratio  of  moisture 
present  to  the  original  moisture  of  the  mass  may  be  definitely 
known. 

Material  to  Be  Taken. — As  stated  above,  the  first  essential  in  a 
sample  is  that  it  shall  truly  represent  the  mass  of  which  it  is  a 
part.  To  secure  this  result  a  few  fundamental  conditions  must 
be  observed,  as  follows: 

The  gross  sample  must  be  representative  of  the  various  kinds  of 
material  present.  That  is  to  say,  a  mass  of  coal  consists  of  fine 
stuff,  lump,  bone,  slate,  pyrites,  and  other  constituents.  As  a 
rule  the  " fines"  differ  in  composition  from  the  lump,  hence  the 
sample  must  have  these  two  sorts  of  material  in  their  proper 
proportion.  The  same  is  even  more  true  of  slate  or  pyrites,  the 
composition  of  which  differs  widely  from  that  of  the  major  part 
of  the  mass.  An  undue  amount  of  such  material  would  cause  a 
serious  disturbance  in  the  accuracy  of  the  sample. 

Amount. — In  procuring  a  representative  sample  a  large  element 
of  safety  resides  in  the  quantity  taken.  In  general,  the  larger  the 
amount,  the  more  representative  it  will  be.  However,  conditions 
differ.  It  is  easier,  for  example,  to  procure  an  even  sample  from 
the  face  of  a  working  vein  or  from  a  carload  of  screenings  than 
from  a  carload  or  other  mass  of  lump  or  run-of-mine  coal.  In 
the  latter  case  larger  amounts  should  be  taken  than  in  the 
former. 

The  limits  of  practicability  for  the  proper  handling  of  the 
sample  must  however  be  considered.  In  general,  the  gross 
sample  should  weigh  approximately  from  200  to  600  Ib.  Doubt- 


SAMPLING  OF  COAL  13 

less  200  Ib.  of  screenings,  taken  with  fairly  good  distribution 
throughout  the  unloading  of  a  40-  or  50-ton  car,  will  yield  a 
very  true  sample.  The  difficulties  increase  greatly  with  the 
increase  of  the  size  of  the  particles,  as  in  the  case  of  lump  or 
mine-run  coal.  If  mechanical  appliances  for  grinding  are  avail- 
able, the  larger  amount  should  be  taken,  but  a  smaller  sample 
well  crushed  down  before  quartering  is  better  than  a  greater 
mass  quartered  down  while  the  particles  are  still  in  larger 
pieces. 

Ratio  of  Size  to  Mass. — Assuming  that  the  sample  as  taken  is 
made  up  of  the  various  kinds  of  material  in  proper  proportion,  the 
next  important  item  is  to  maintain  these  variables  in  their  ratios 
throughout  the  process  of  reducing  the  gross  amount  to  a  small 
working  or  laboratory  sample.  To  insure  this  result,  there  must 
be  maintained  a  certain  ratio  of  size  of  the  particles  to  size  or 
weight  of  the  mass.  This,  as  a  rule,  is  based  on  a  formula  which 
provides  that  the  weight  of  the  largest  piece  of  impurity  shall 
have  a  ratio  to  the  weight  of  the  mass  of  about  2:10,000.  .  For 
example,  a  mass  weighing  10,000  grams,  or  about  22  Ib.,  should 
contain  no  particles  weighing  more  than  2  grams.  This  would 
mean  that  the  largest  particle,  as  for  example,  a  piece  of 
iron  pyrites,  must  not  be  over  J  in.  in  its  greatest  diameter. 
Each  piece  of  impurity  of  this  size  improperly  distributed 
would  represent  a  possible  error  of  approximately  ±  0.02  per 
cent. 

The  final  ratio  of  sizes,  however,  should  be  determined  by  the 
methods  available  for  grinding.  With  mechanical  appliances 
for  obtaining  the  smaller  sizes,  a  table  of  ratios  with  greater 
safety  limits  can  be  adopted  than  is  perhaps  practicable  where 
the  crushing  is  done  by  hand.  If  a  power  crusher  is  available, 
the  entire  sample  should  be  passed  through  the  mill  and  reduced 
to  a  size  which  will  pass  a  J-in.  screen.  If  the  crushing  must  be 
done  by  hand,  the  first  reduction  in  size  of  the  particles  should  be 
such  that  the  entire  mass  will  pass  through  a  1-in.  screen.  When 
by  quartering,  the  sample  is  reduced  to  100  Ib.,  the  size  of  the 
particles  should  be  further  reduced  to  a  size  that  will  pass  a 
J-in.  screen,  and  with  a  50-lb.  sample  in  hand  the  crushing  should 
be  carried  to  J-in.  mesh.  The  subdivisions  with  their  respective 
sizes  are  shown  in  tabular  form  as  follows: 


14  FUEL,  GAS,  WATER  AND  LUBRICATION 

TABLE  I. — SIZE  OF  MESH  FOR  DIFFERENT  SUBDIVISIONS  OF  SAMPLE 


Weight  of  subdivisions  of  sample 
(pounds) 


Size  of  mesh  to  which  each  sub- 
division should  be  broken  (inches) 


500 

250 

125 

60 

30 


Illinois  coals  are  easily  crushed  in  mills  which  are  available  at 
little  expense.     Hence,  it  is  entirely  reasonable  to  require  that 


FIG.  7. — Coal  grinder  of  the  coffee-mill  type. 

gross  samples,  when  reduced  in  mass  to  50  or  75  lb.,  shall  be 
passed  through  a  mill  set  for  grinding  to  approximately  J  in. 
For  this  work,  a  mill  which  is  not  of  the  jaw  crusher  or  roller  type 
is  preferred,  since  these  types  produce  too  large  a  percentage 
of  fine  material,  and  the  harder  pieces  of  slate,  especially  those  of 
flaky  or  plate-like  structure,  are  liable  to  pass  in  pieces  having 
inadmissably  large  dimensions  in  two  directions,  even  though  the 
adjustment  used  would  seem  to  be  fine  enough  to  prevent  the 
passage  of  such  material.  A  grinder  of  the  coffee-mill  type  or 
one  with  projecting  teeth  on  the  grinding  surfaces  will  be  found 


SAMPLING  OF  COAL 


15 


to  produce  a  more  uniform  size  and  the  minimum  amount  of  dust. 
The  grinding  surfaces  of  such  a  machine  are  shown  in  Fig.  7. 

Mixing  and  Subdividing. — As  a  further  precaution  in  main- 
taining a  correct  distribution  of  the  various  constituents,  empha- 
sis is  placed  upon  the  necessity  of  thorough  mixing,  followed  by 
an  even  selection  of  the  remaining  subdivisions.  It  is  true  that  fine 
grinding  contributes  materially  to  this  end  but  further  care  is 
necessary.  It  is  entirely  practicable  to  mix  a  50-lb.  sample, 
ground  as  above  described,  by  rolling  in  an  oilcloth  about  5  ft. 
square.  This  is  accomplished  by  taking  one  corner  of  the  cloth 


FIGS.  8  and  9. — Flattening  the  heap  of  coal  and  then  quartering  the  pile- 


and  carrying  it  over  the  pile  towards  the  diagonally  opposite 
corner  so  as  to  cause  the  mass  to  roll  over  upon  itself,  then 
reversing  the  motion  and  repeating  the  process  with  the  other 
two  corners.  Fifteen  or  twenty  such  alterations,  depending 
somewhat  upon  the  size  of  the  sample,  should  be  sufficient  to 
effect  an  even  mixture.  After  mixing,  the  process  of  coning  and 
quartering  should  be  followed  as  illustrated  in  the  cut,  Figs.  8 
and  9.  Opposite  quarters  are  rejected  until  the  final  sample 
amounts  to  about  5  Ib.  This  is  sealed  in  an  airtight  container, 
and  forwarded  to  the  laboratory  for  analysis. 

The  subdividing  of  the  larger  sample,  to  reduce  it  to  a  con- 
venient size  for  transmission  to  the  laboratory,  requires  special 
consideration  as  having  an  important  bearing  on  the  mainte- 


16 


FUEL,  GAS,  WATER  AND  LUBRICATION 


nance  of  the  correct  ratio  of  constituents.     This  may  be  best 
shown  by  the  data  given  in  Table  II. 

TABLE  II. — ASH  VARIATIONS  IN  DIFFERENT  SIZES  OBTAINED  FROM 
DUPLICATE  SAMPLES 


Series 

Mesh 

1 

Dupli- 
cate 
halves 

Per  cent 
of  each 
size 

Ash 

a  and  b  composited 
by  calculation      j 

lt 

On  20  

a 

41  7 

14.11 

b 

48.4 

14.00 

ti 

Through  20  
On  60  

a 
b 

41.7 
37.9 

15.55 
15.42 

a        16.32 

b                        15  86 

1. 

Through  60 

16  6 

23  89 

b 

13.7 

23.65 

Average  16.09 

2i 

On  20  

a 

29.1 

15.91 

b 

25.0 

15.68 

22 

Through  20  
On  60  

a 
b 

48.4 
51.9 

16.23 
16.06 

a  17.90 

b                    .17.80 

2a 

Through  60 

d 

22  5 

24  09 

b 

23.1 

23.98 

Average  17.85 

Note  in  this  table  that  series  1  and  2  are  3-lb.  samples  taken  by 
subdividing  in  the  same  manner  the  same  gross  sample  of  about 
30  Ib.  Each  sample  was  ground  to  eight-mesh  and  sized.  It 
will  be  seen  that  in  series  1,  duplicates  a  and  b  had  16.6  and  13.7 
per  cent  of  the  60-mesh  size,  whereas  in  series  2  the  duplicates  a 
and  b  had  22.5  and  23.1  per  cent  respectively.  Note  further, 
the  great  increase  in  ash  in  the  fine  size  as  compared  with  the 
ash  in  the  coarse  material.  For  example,  series  1  having  an 
average  of  14  per  cent  of  ash  in  the  coarse  size  has  an  average 
of  23.75  per  cent  in  the  fine  portion.  A  similar  increase  in  ash 
is  seen  in  the  corresponding  sizes  in  series  2.  The  ultimate  ash 
average  for  series  1  is  16.09  per  cent  and  for  series  2  it  is  17.85 
per  cent.  These  values  vary  consistently  with  the  variation  in 
the  percentages  of  fine  material  in  the  respective  series.  On  the 
other  hand,  the  duplicate  halves  a  and  b  throughout,  because  of 


SAMPLING  OF  COAL  17 

their  uniformity  resulting  from  the  sizing  process,  show  result 
in  the  several  pairs  which  check  very  closely. 

The  values  as  presented  in  the  table,  therefore,  show  clearly 
that  in  the  process  of  subdividing  the  gross  sample  and  in  the  fur- 
ther reduction  of  the  sample  as  received  at  the  laboratory,  great 
care  must  be  exercised  to  see  that  no  part  of  the  manipula- 
tion is  of  such  a  nature  as  will  promote  segregation  of  the 
constituents. 

Riffling. — A  riffle  constructed  according  to  the  pattern  shown 
in  Fig.  10  may  be  used  to  advantage  after  the  sample  has  been 
reduced  by  quartering  to  about  5  Ib.  At  this  stage  the  sample  is 


FIG.  10. — Riffle. 

ground  to  J-in.  size,  hence  the  riffle  openings  may  be  \  in.  in 
width.  With  this  variation  in  the  openings  the  riffle  as  shown 
in  Fig.  10  is  substantially  the  one  described  in  the  Bulletin  of  the 
Ohio  Geological  Survey,  No.  9,  p.  313,  1908.1 

Segregation  may  occur  where  least  expected,"for  example,  in 
the  use  of  a  riffle,  if  the  material  is  added  from  the  scoop  more 
rapidly  than  it  can  pass  through  the  openings,  thereby  piling 
up  in  the  riffle  hopper,  the  material  tends  to  form  itself  into 
cone-shaped  masses,  down  the  sides  of  which  the  particles  may 
flow  more  readily  in  one  direction  than  in  another,  depending  on 
the  freedom  of  the  opening.  Such  conditions  promote  marked 
segregation.  Riffles  with  large  hoppers  and  small  grid  areas 
are  not  of  good  construction.  Numerous  tests  on  this  point 

^ee  also  "Standard  Methods"  of  the  American  Society  for  Testing 
Materials,  1916,  p.  552.  Also  same  volume  for  sampling  details,  pp.  544- 
549. 

2 


18  FUEL,  GAS,  WATER  AND  LUBRICATION 

have  been  made.1  One  set  only  is  given  here.  The  sample  No.  1 
of  Table  II,  but  not  separated  into  the  various  sizes,  shows 
an  ash  content  of  16.09  per  cent.  The  two  halves  obtained  by 
proper  feeding  of  the  riffle  gave  16.07  and  16.26  per  cent,  or  a 
difference  of  0.19  per  cent.  By  rapid  feeding,  sufficient  for  the 
material  to  pile  up  in  the  hopper,  the  two  halves  gave  ash  values 
of  14.35  and  17.87  per  cent  respectively,  or  a  difference  of  3.52 
per  cent. 

Sampling  a  Carload. — A  car  of  coal  may  be  sampled  to  the  best 
advantage  in  the  process  of  unloading.  An  occasional  half 
shovelful  should  be  thrown  into  a  proper  receptacle  so  that  by 
the  time  the  car  is  unloaded  approximately  200  lb.,  evenly  dis- 
tributed throughout  the  load  will  have  been  taken.  This  will 
mean  about  one-half  shovelful  for  every  10  full  scoops.  They  are 
best  taken  in  the  process  of  shoveling  from  the  bottom  of  the  car, 
since  the  top  coal  rolls  down  and  mixes  fairly  evenly  with  the 
bottom.  It  should  be  kept  in  mind  that  in  taking  a  sample  there 
must  be  obtained  the  different  sizes  of  coal,  fine  and  coarse  in  their 
proper  proportions  from  the  entire  cross-section  of  the  mass,  and 
also  an  even  distribution  of  the  sample  lengthwise  of  the  car. 
Even  greater  care  must  be  taken  to  guard  against  loss  of  moisture 
in  the  process  of  collecting  and  in  reducing  the  gross  sample  for 
the  reason  that  as  a  rule  the  relative  humidity  outside  of  the 
mine  is  lower  and  the  tendency  of  the  moisture  to  leave  the  coal 
is  correspondingly  increased. 

It  has  been  shown  in  Table  II,  that  the  finer  particles  of  a  coal 
mass  are  higher  in  ash  and  hence  have  a  greater  specific  gravity. 
They  are  therefore  more  likely  to  separate  by  gravity  from  the 
coarser  material.  On  this  account,  if  a  car  is  to  be  sampled 
without  unloading,  it  is  necessary  to  dig  well  toward  the  bottom 
in  order  to  obtain  a  representative  sample.  Three  trenches 
should  be  dug  crosswise  of  the  load,  one  near  each  end  and  one 
near  the  middle  of  the  car.  These  trenches  should  go  down 
nearly  to  the  bottom  of  the  mass  and  each  size  be  taken  as  nearly 
as  possible  in  its  proper  proportion.  Lump  and  run-of-mine  lots 
are  much  more  difficult  to  sample  than  screenings,  but  it  should 
.be  noted  that  screenings  may  vary  greatly,  for  not  infrequently  a 
car  is  partially  loaded  from  one  bin  and  finished  from  another 

llll.  S.  G.  S.  Coop.  Bull  3,  p.  25,  191G. 


SAMPLING  OF  COAL  19 

which  may  be  of  a  different  size  and  composition.  After  ob- 
taining the  gross  sample,  the  methods  to  be  followed  are  the 
same  as  those  already  given. 

Composite  Samples. — It  is  often  desirable  to  composite  a 
number  of  samples.  In  this  way  a  single  sample  may  be  made 
to  represent  a  much  larger  quantity  of  coal  and  thus  cut  down 
the  time  and  expense  involved  in  procuring  the  analytical  data. 
In  this  procedure,  however,  it  must  be  remembered  that  even 
greater  care  should  be  exercised  in  taking  the  several  component 
samples.  The  amount  of  each  sample  entering  into  the  com- 
posite must  be  in  proportion  to  the  mass  which  it  represents,  and 
finally  a  thorough  and  positive  mixing  of  the  composited  mass 
must  be  effected  before  quartering  down  the  same  to  the  usual 
5-lb.  quantity. 

It  is  convenient  to  determine  the  amount  of  each  sample  to  be 
taken  by  employing  an  aliquot  system  of  weights.  For  illus- 
tration: Suppose  we  adopt  1  gram  to  the  100  Ib.  as  the  unit 
which  shall  enter  into  the  composite.  Then  a  100,000-lb.  car  of 
coal  should  be  represented  by  1,000  grams.  In  compositing, 
therefore,  the  total  amount  of  each  sample  will  not  be  taken,  but 
instead  an  aliquot  proportion  which  will  give  to  each  car  lot  its 
due  amount.  It  is  preferable  to  use  such  a  factor  as  shall  utilize 
the  major  part  of  the  several  5-lb.  samples.  In  this  way  the 
gross  composite  from  10  cars  would  aggregate  20  or  30  Ib.  in 
weight.  It  should  be  coned  and  quartered  until  a  thoroughly 
homogeneous  mass  of  about  5  Ib.  is  obtained,  as  already  de- 
scribed. For  this  procedure  it  is  obvious  that  the  necessary  data 
should  accompany  the  various  samples.  A  ticket  inserted  in  the 
can  before  sealing  should  give  the  data  needed. 

A  convenient  form  is  as  follows: 

From Date .19.  . 

(Name  of  institution)  .  (When  taken) 

Kind  of  coal 

Car  initials Car  No 

Net  weight 

Weight  taken  for  composite1 

Weight  of  quarter  taken  for  dust 

Weight  of  dust  in  quarter  taken 

1  Divide  the  net  weight  by  2  and  place  a  decimal  point  after  the  first 
figure  of  the  quotient. 


20 


FUEL,  GAS,  WATER  AND  LUBRICATION 


Mechanical  Sampling. — Numerous  attempts  have  been  made 
to  devise  a  mechanical  method  for  taking  samples.  While  it  is 
possible,  by  such  means  to  eliminate  the  personal  equation,  it 
is  difficult  to  avoid  segregation  or  an  uneven  distribution  of 
coarse  and  fine  material.  In  the  sample  grinder  illustrated  in 
Fig.  11,  there  is  an  evident  advantage  that  with  such  a  power 
grinder  larger  samples  may  be  handled,  thus  dividing  rather  than 
multiplying  the  errors.  The  illustration  shows  the  grinder  opened 
for  cleaning,  at  the  end  of  the  operation.  Both  the  central 


FIG.   11.- — Grinder  opened  for  cleaning. 

grinding  cone  and  the  wing  stirrer  underneath  may  be  lifted  out 
for  cleaning  the  entire  grinding  and  distributing  chamber.  The 
sampling  feature  is  so  arranged  that  an  aliquot  part,  approxi- 
mately 10  per  cent,  is  delivered  into  the  small  receptacle  in  the 
process  of  grinding  the  original  mass.  In  use  of  such  a  sample 
grinder,  the  facility  with  which  the  material  may  be  passed 
through  makes  it  possible  to  take  much  larger  initial  samples. 
For  example,  if  occasional  shovelfuls  are  taken,  well  distributed 
throughout  the  unloading  of  a  car  in  such  an  amount  as  to  yield 
say  40  Ib.  in  the  aliquot  portion,  then  it  is  known  that  approxi- 
mately a  400-lb.  gross  sample  has  been  passed  through  the 
grinder. 

Doubtless  the  best  method  for  determining  the  accuracy  of 


SAMPLING  OF  COAL 


21 


the  sample  delivered  by  the  apparatus  is  to  compare  the  ash 
values,  water-free  basis,  as  obtained  from  the  small  sample  with 
the  ash  value  from  the  main  portion,  sampled  by  carefully 
quartering  down  by  hand  in  the  usual  manner.  A  number  of 
tests  of  this  sort  are  shown  in  Table  III. 

TABLE  III. — ACCURACY  OF  SAMPLE  GRINDER 

Comparison  of  ash  values.     Dry  basis 
Samples  A  and  B  obtained  from  main  portion  by  quartering  and   riffling 


Labora- 
tory 
number 

Coal 

Ash  in 
small 
sample  as 
delivered 
by  grinder 

A 
Ash  in  main 
portion 
sampled  by 
quartering 
and  riffling 

B 

Ash  in  main 
portion 
Duplicate  of 
A  —  opposite 
quarter 

8661 

Vermilion  Co.  Screenings  .... 

15.53 

15.22 

15.72 

8664 

Vermilion  Co.  Screenings  .... 

14.52 

14.52 

14.65 

8367 

Vermilion  Co.  Screenings  .... 

19.19 

19:88 

19.72 

8670 

Vermilion  Co.  Screenings  .... 

17.43 

17.78 

17.58 

Another  test  has  been  applied  as  follows:  The  samples  as 
obtained  in  the  process  of  grinding  10  gross  samples  were 
delivered  into  a  common  receptacle  in  their  proper  proportions 
for  compositing.  Without  further  mixing,  the  mass  of  approxi- 
mately 40  Ib.  was  poured  into  the  grinder.  The  accuracy  of  the 
small  sample  thus  obtained  was  determined  as  before,  by  com- 
parison of  ash  values.  The  main  portion  was  sampled  again  by 
pouring  through  the  mill  a  second  time  for  a  duplicate  aliquot 
delivery.  The  results  are  shown  in  Table  IV.  In  both  of  these 
tables  the  agreement  between  the  sample  delivered  by  the  mill 
and  the  sample  obtained  from  the  main  portion  is  very  satis- 
factory, especially  when  we  consider  the  variations  inherent  in 
the  processes  of  analysis  for  high-ash  coals. 

Moisture  Control. — The  further  essential  in  taking  and  pre- 
paring a  sample  relates  to  the  free  moisture  present,  and  requires 
that  the  changes  in  moisture  content  "must  be  under  exact 
control  so  that  at  any  stage  the  ratio  of  the  moisture  present  to 
the  original  moisture  of  the  mass  may  be  definitely  known." 

In  coals  of  this  region  especially,  where  the  moisture  in  the  coal 
as  it  comes  from  the  mine  averages  from  10  to  15  per  cent  the 
tendency  toward  moisture  changes  is  very  marked.  For  ex- 


22 


FUEL,  GAS,  WATER  AND  LUBRICATION 


TABLE  IV. — ACCURACY  OF  SAMPLE  GRINDER 

By  comparison  of  ash  values.     Dry  basis 
Duplicate  sample  obtained  by  second  passage  of  main  portion  through  mill 


Laboratory 
number 

Coal  (screenings) 

A 

First  aliquot 
of  10  per  cent 
as  delivered 

B 

Second 
aliquot  of 
main  portion 

8668 

Moult  rie  County              

19.61 

19.60 

8934 

Moult  rie  County 

20  32 

20  38 

8961 

Moultrie  County  

20.94 

21.13 

8973 

Moultrie  County        

19.21 

19.82 

9011 

Moultrie  County 

19  21 

19.17 

9013 
9025 

Moultrie  County  
Montgomery  County  

19.62 
13.69 

19.41 
13.44 

9143 

Moultrie  County                    .  .  . 

19  64 

19.67 

9147 

jyjoultrie  County 

19  83 

20  03 

9162 

Moultrie  County  

20.14 

20.26 

9160 

Montgomery  County 

14.17 

13.89 

9180 

Moultrie  County 

19  32 

18  94 

9185 
9195 

Montgomery  County  
Moultrie  County               

13.30 
19.72 

13.48 
19.90 

9197 

Moultrie  County 

18  61 

19.18 

9240 

Montgomery  County  

13.20 

12.95 

9242 

Moultrie  County  

19.82 

19.89 

9244 

Moultrie  County 

18  93 

18.96 

9268 

Montgomery  County 

13  48 

13.43 

ample,  the  process  of  crushing  down  the  larger  sizes  affords  an 
opportunity  for  the  escape  of  moisture.  Again,  if  the  coal  is 
spread  out  on  the  floor  of  a  hot  boiler  room  or  left  exposed  to 
currents  of  air  for  any  length  of  time  there  will  be  a  serious  change 
in  the  moisture  factor.  Another  practice  sometimes  followed 
is  that  of  assembling  the  various  increments  of  the  gross  sample 
in  a  sack  or  other  receptacle  permitting  a  relatively  free  trans- 
mission of  air.  Samples  kept  in  this  manner  for  any  length  of 
time  or  shipped  in  such  containers  will  have  a  moisture  content 
quite  different  from  the  original. 

The  methods  employed,  therefore,  in  collecting  and  reducing  a 
gross  sample  must  have  special  reference  to  this  tendency  on  the 
part  of  the  free  moisture  to  escape.  The  work  should  be  done 


SAMPLING  OF  COAL  23 

rapidly  in  a  room  at  or  below  the  normal  temperature  and,  so 
far  as  possible,  with  the  use  of  closed  apparatus  which  admits  of 
the  least  possible  exchange  of  the  contained  air.  Precaution- 
ary measures  of  this  sort  should  be  made  at  the  very  outset. 
The  gross  sample,  which  is  made  up  of  small  increments  collected 
usually  over  a  considerable  length  of  time,  should  be  enclosed  in  a 
tight  box  or  clean  garbage  can  having  a  tightly  fitting  cover  which 
can  be  closed  and  locked  against  the  possibility  of  change  until 
the  time  for  grinding  and  reducing. 

Dust  Determinations. — From  the  preceding  discussion  it  will 
be  at  once  obvious  that  with  coals  of  the  Illinois  type  where  high 
ash  of  the  fine  material  is  a  characteristic  feature,  a  specification 
as  to  the  limit  of  dust  or  duff  allowable  in  screenings  is  often  or 
indeed  usually  embodied  in  coal  specifications.  Dust  determi- 
nations are  not  necessary  of  course  on  run-of-mine  or  lump  coal. 

For  obtaining  the  percentage  of  dust  in  screenings  or  slack  a 
200-lb.  sample  as  taken  in  the  ordinary  procedure  is  coned  and 
quartered  by  the  standard  method.  One  of  the  quarters,  about 
50  lb.,  is  placed  in  a  weighed  metal  basket  and  the  weight  taken. 
It  is  then  passed  through  a  J-in.  screen  into  a  second  weighed 
basket.  The  weight  of  the  material  passing  through  is  noted. 
Both  of  these  factors  are  placed  on  a  ticket,  and  both  portions  of 
coarse  and  fine  material  are  rejected. 

Divide  the  weight  of  the  material  passing  the  i-in.  screen 
by  the  total  weight  of  the  quarter  taken  and  multiply  by  100. 
This  will  give  the  percentage  of  dust  present  in  the  coal.  The 
remainder  of  the  sample  should  be  coned  and  quartered  to 
about  25  lb.  or  passed  through  the  sample  grinder  and  then 
riffled  as  already  described. 

Laboratory  Sample. — The  preceding  discussion  relates  mainly 
to  the  taking  of  the  gross  sample.  Ordinarily  it  should  be  about 
3  to  5  lb.  in  amount  and  sealed  in  a  manner  to  preclude  the 
possibility  of  change  in  moisture  content  while  being  transported 
to  the  laboratory. 

The  preparation  of  the  working  sample  for  the  laboratory  is 
usually  considered  as  a  separate  matter  from  that  of  the  gross 
sampling  of  the  mass.  It  should  be  carried  out  by  the  chemist 
or  under  his  immediate  supervision.  After  taking  approxi- 
mately 100  grams  for  total  moisture  as  described  under  "Analy- 


24  FUEL,  GAS,  WATER  AND  LUBRICATION 

sis"  in  the  chapter  following,  the  main  sample  is  air  dried  to 
approximately  constant  weight  or  to  a  moisture  content  of  from 
2  to  4  per  cent  and  passed  through  a  coffee-mill  grinder  to  reduce 
it  to  a  size  which  will  pass  through  a  10-mesh  sieve.  This  is 
riffled  down  to  about  500  grams  and  placed  in  the  ball  mill  for 
fine  grinding.  The  buckboard  may  also  be  used  for  this  purpose, 
in  which  case  a  smaller  amount,  about  100  grams,  should  be  taken. 
About  50  grams  of  the  60-mesh  material  is  placed  in  a  small 
bottle  with  rubber  stopper  from  which  the  samples  for  analysis 
are  weighed. 

It  is  well  to  remember  that,  even  under  these  conditions  of 
storing,  changes  in  the  sample  occur  such  as  segregation,  due  to 
the  settling  of  the  heavier  particles,  oxidation  which  results  in  a 
slight  increase  of  free  moisture,  and  especially  if  the  moisture  is 
high,  above  4  or  5  per  cent,  there  is  a  very  appreciable  change  in 
the  iron  pyrites  from  FeS2  to  FeS04  +  7H2O. 


CHAPTER  IV 
ANALYSIS  OF  COAL 

Moisture  and  Nomenclature. — The  topic  of  moisture  control 
has  already  been  discussed,  emphasis  having  been  laid  upon  the 
fact  that  at  any  stage  of  the  processes  the  exact  ratio  of  the  mois- 
ture present  to  the  moisture  of  the  original  mass  must  be  defi- 
nitely known.  This  implies  that  moisture  changes  do  occur. 
Indeed  three  moisture  conditions  exist  and,  since  under  each 
condition  all  of  the  accompanying  factors  are  modified  to  meet 
the  specific  change  in  moisture,  a  special  designation  is  applied 
to  the  coal  for  each  one  of  these  conditions. 

Coal  with  all  of  the  normal  moisture  present  is  designated  as 
"wet"  coal  or  coal  "as-received."  It  relates  to  the  moisture  at 
the  time  of  taking  the  sample.  All  of  the  detail  of  the  processes 
for  collecting  and  reducing  the  gross  sample  up  to  and  including 
the  item  of  sealing  and  shipping  the  5-lb.  sample  involves  the 
preservation  of  this  initial  moisture  without  loss. 

The  second  moisture  status  is  that  wherein  the  "wet"  or  "as- 
received  "  coal  has  been  dried  to  a  point  of  substantial  equilibrium 
with  the  moisture  of  the  air,  so  that  in  an  atmosphere  of  average 
humidity  it  would  take  on  or  lose  additional  moisture  very  slowly 
or  not  at  all.  In  this  condition  the  coal  sample  is  said  to  be 
"air  dry."  This  is  the  condition  to  which  the  chemist  must 
bring  the  sample  in  order  that  the  processes  of  finer  grinding  and 
weighing  may  be  carried  on  without  change  in  the  moisture 
factor.  Obviously  the  amount  of  moisture  lost  in  passing  from 
the  "wet"  or  "as-received"  condition  to  the  "air-dry"  condition 
must  be  carefully  measured.  The  factor  thus  determined  is 
designated  as  the  "loss  on  air  drying."  By  use  of  it  all  of  the 
values  obtained  from  analysis  of  the  coal  in  the  "air-dry" 
state  may  be  calculated  to  the  "wet"  or  "as-received"  condition. 

The  third  condition  recognized  is  that  of  "dry"  coal.  This  is 
sometimes  designated  as  the  "oven-dry"  or  "moisture-free" 

25 


26  FUEL,  GAS,  WATER  AND  LUBRICATION 

state.  All  of  the  values  found  for  the  coal  in  the  "air-dry" 
condition  may  be  transferred  by  calculation  and  made  to  apply 
to  the  coal  as  "oven-dry."  The  necessary  factor  in  this  case 
is  the  loss  of  moisture  obtained  from  drying  the  " air-dry"  sample 
at  or  slightly  above  steam  temperature,  as  105°C.  for  1  hr.  It 
is  not  intended  here  to  give  directions  for  carrying  out  these 
processes.  The  terms  employed,  however,  are  of  so  frequent 
occurrence,  and  in  many  cases  enter  so  vitally  into  a  correct 
understanding  of  the  methods  upon  which  certain  values  are 
based  in  the  making  of  estimates  and  arriving  at  fuel  settlements 
that  at  least  a  brief  reference  seems  desirable. 

Carelessness  in  the  use  of  these  terms  leads  to  much  confusion. 
The  chemist  and  the  engineer  are  not  always  in  agreement  as  to 
their  meaning.  The  results  as  obtained  by  chemical  analysis 
upon  the  air-dry  sample  are  of  little  use  to  the  engineer,  whose 
basis  of  reference  is  to  the  "as-received"  or  to  the  "dry"  basis. 
For  the  purpose  of  the  engineer  it  is  necessary,  therefore,  to 
calculate  the  results  which  are  obtained  on  the  air- dry  sample 
back  to  the  "wet"  coal  and  also  to  the  "dry"  basis.  These 
values  are  the  only  ones  that  should  be  reported.  The  factors 
obtained  on  the  "air-dry"  basis  are  for  the  chemist  only,  and 
have  no  significance  for  any  one  else. 

It  will  be  evident  at  once  that  throughout  all  of  the  handling 
of  a  coal  sample  there  must  be  exact  control  of  the  free  moisture 
and  knowledge  of  the  amount  present  at  the  various  stages  of 
reference  in  order  that  calculations  may  be  made  from  one 
basis  to  another.  Two  methods  are  in  common  use.  One  takes 
account  of  the  moisture  loss  on  air  drying  and  again  the  moisture 
loss  on  passing  from  the  "air-dry"  to  the  "oven-dry"  or  "mois- 
ture-free" condition.  With  these  two  factors  in  hand  the  "total 
moisture"  on  the  sample  as  received  is  derived  by  calculation. 
This  method  requires  careful  handling  of  the  material  in  order 
that  no  unmeasured  losses  or  accessions  of  moisture  occur  in  the 
various  operations  of  grinding,  riffling,  etc. 

The  other  procedure  and  the  one  least  liable  to  error  is  carried 
out  by  taking  a  "total  moisture  sample"  at  once  upon  opening 
the  5-lb.  laboratory  sample.  This  will  be  about  100  grams  in 
amount.  It  should  be  put  through  a  grinder  at  once,  reducing 
it  to  about  10-mesh  size,  and  retained  in  a  sample  bottle  with 


ANALYSIS  OF  COAL  27 

rubber  stopper.  Five-gram  samples  are  taken  for  total  moisture 
determinations. 

Having  thus  the  total  moisture  on  the  coal  "as  received," 
the  main  sample  may  be  air-dried  without  reference  to  the  loss 
on  air  drying.  The  moisture  found  on  oven  drying,  and  the 
total  "as  received"  moisture  furnish  all  the  data  needed  for 
calculating  to  the  two  bases  for  reporting,  namely  the  "as- 
received"  and  the  "dry"  or  moisture-free  condition. 

Calculations. — To  calculate  the  percentage  values  obtained  on 
"air-dry"  coal  to  the  "dry-coal"  basis,  divide  each  constituent 
by  (100  —  w)  in  which  w  is  the  moisture  present  in  the  "air-dry" 
sample.  The  moisture  factor  for  the  "dry"  coal  is  omitted  of 
course,  and  the  sum  of  the  resulting  constituents  should  total  100 
per  cent. 

To  calculate  from  the  "air-dry"  values  to  the  "wet,"  or  "as- 
received"  condition  multiply  each  percentage  for  the  "air-dry" 
state  by  (100  —  Z)  in  which  I  is  the  loss  on  air  drying.  The 
moisture  factor  thus  derived  plus  the  loss  on  air  drying  equals  the 
total  moisture  in  the  "wet"  coal.  This  and  the  other  factors 
calculated  as  described  should  equal  100  per  cent.  Where  a 
total  moisture  factor  is  obtained  the  calculation  is  made  to  the 
"wet"  basis  from  the  "dry"  or  "moisture-free"  state  by  multi- 
plying the  dry  values  by  (100  —  t)  in  which  t  is  the  total  moisture. 

Methods  of  Analysis. — Coal  may  be  subjected  to  either  the 
ultimate  or  proximate  method  of  analysis.  In  the  former, 
beside  the  moisture,  ash,  and  sulphur  factors,  a  determination  is 
made  of  the  constituent  elements  comprising  the  organic  substance 
of  the  coal;  namely,  carbon,  hydrogen,  nitrogen,  and  oxygen. 

In  the  proximate  method,  besides  the  moisture,  ash,  and  sulphur, 
there  are  determined,  instead  of  the  elemental  substances  of  the 
organic  part,  only  volatile  matter  and  fixed  carbon.  The  ulti- 
mate analysis  furnishes  data  from  which  the  heat  value  of  the 
coal  can  be  calculated.  The  proximate  analysis  gives  the  neces- 
sary data  for  judging  of  the  kind  and  general  character  of  the  coal. 
It  is  the  proximate  method  which  will  be  chiefly  considered,  the 
main  object  being  to  discuss  the  significance  of  the  various 
factors,  methods  of  calculation,  etc.  The  analytical  methods 
are  taken  up  elsewhere  under  the  directions  for  the  laboratory 
processes. 


28 


FUEL,  GAS,  WATER  AND  LUBRICATION 


General  Plan. — The  general  purpose  involved  in  making 
a  chemical  analysis  of  coal  is  to  furnish  a  basis  for  estimating 
values.  In  its  simplest  form  it  consists  in  separating  the  inor- 
ganic or  non-combustible  from  the  organic  or  heat-producing 
material.  The  following  outline  may  serve  as  an  illustration: 


COAL 


Inorganic  or 
Non-combustible 


Moisture 


Organic  or 
Combustible 


Plant  Ash 

Clayey  Matter 

Calcium  Sulphate 

Calcium  Carbonate 

Salt 

Iron  Pyrites 

(  Complex 

\  Hydrocarbon 

[  Compounds 


Water 


Ash 


Combustible 


It  will  be  seen  from  the  diagram  that  the  constituents  of  funda- 
mental importance  are  in  reality  only  three  in  number:  Water, 
ash,  and  combustible  matter.  The  meaning  and  use  of  these 
values  especially  in  some  sort  of  their  modified  or  corrected  forms 
may  be  made  of  great  service  in  connection  with  the  purchase 
and  sale  of  coal  on  specification. 

The  Interpretation  of  Moisture  Values. — The  significance  of 
the  factor  for  moisture  is  important.  In  coals  with  high  moisture 
in  the  vein,  a  large  shrinkage  in  weight  occurs  in  the  process  of 
shipment.  In  the  majority  of  cases,  settlement  is  made  upon  the 
basis  of  the  mine  weights.  This  loss  of  moisture,  therefore,  falls 
ultimately  upon  the  consumer. 

There  is  usually  a  certain  agreement  also  between  combined 
oxygen  or  the  water  of  constitution  and  the  content  of  free 
moisture  in  the  vein  sample;  the  higher  the  moisture,  the  more 
combined  oxygen  and  the  smaller  the  percentage  of  combustible 
in  the  volatile  matter.  For  this  reason  there  are  more  heat 
units  per  pound  of  combustible  (ash  and  moisture  free)  in  Poca- 
hontas  coal,  with  2  per  cent  of  vein  moisture,  than  per  pound  of 
combustible  (ash  and  moisture  free)  in  Illinois  coal,  with  12 
per  cent  of  moisture  in  the  vein  sample.  The  vein  moisture, 


ANALYSIS  OF  COAL  29 

therefore,  becomes  to  a  very  considerable  extent  an  index  of  the 
type  or  composition  of  the  organic  part  of  the  coal.  These 
variations  in  property  will  be  discussed  somewhat  further  under 
the  topic  of  "Unit  Coal." 

Ash. — Ash  is  the  inorganic  constituent  of  the  coal  aside  from 
water.  As  commonly  defined,  it  is  the  residue  left  after  burning 
and  is  made  up  of  complex  substances  such  as  sand,  shale  or 
kaolin,  gypsum,  calcium  carbonate,  iron  pyrites,  etc.  But,  from 
the  list  it  is  evident  that  there  is  much  opportunity  for  loss  of 
constituents  such  as  combined  water  and  C02  in  the  process 
of  burning,  which,  if  not  corrected  for,  come  to  be  reckoned  as 
part  of  the  combustible  matter.  There  have  come  into  use, 
therefore,  in  connection  with  the  ash  determination  two  terms 
expressive  of  this  material,  namely,  "ash  as  weighed"  or  simply 
"ash,"  and  "corrected  ash." 

The  use  of  a  corrected  ash  factor  is  primarily  of  interest  in 
the  accurate  determination  of  the  amount  of  active  or  organic 
matter  present.  Thus,  unless  the  line  of  demarcation  between 
the  organic  and  inorganic  substance  is  properly  and  precisely 
drawn,  we  do  not  have  a  correct  unit  for  the  true  combustible 
material.  This  point  will  be  better  understood  from  the  dis- 
cussion of  "Unit  Coal"  in  Chapter  V. 

Sulphur. — This  constituent  of  the  coal  is  made  a  matter  of 
separate  determination.  The  question  might  be  raised  as  to 
whether  the  sulphur  should  not  be  grouped  with  the  true  coal  sub- 
stance since  it  contributes  somewhat  to  the  heat  values  in  the 
burning  process.  But  it  is  distinctly  a  mineral  substance,  varies 
widely  in  amount  and  affects  the  properties  of  the  coal  far  more 
specifically  through  the  ash  than  in  its  contribution  to  the  heat 
volume,  which  is  relatively  small  in  amount.  Moreover,  by 
segregating  it  from  the  heat  producing  constituents  and  taking 
away  the  heat  also  which  may  be  credited  to  it  a  far  more  con- 
sistent value  remains  as  the  true  heat  to  be  credited  to  the  unit- 
coal  substance.  This  procedure  will  be  found  to  have  very  great 
practical  value  as  well  as  being  of  great  advantage  in  the  com- 
parative study  of  coals  for  classification  and  similar  purposes. 
Since  the  sulphur  of  coal  occurs  largely  as  iron  pyrites,  FeS2, 
it  is  generally  believed  that  a  high  sulphur  factor  represents  a  high 
iron  factor  and,  consequently,  a  tendency  for  the  coal  to  clinker 


30  FUEL,  GAS,  WATER  AND  LUBRICATION 

in  burning.  This  does  not  necessarily  always  follow,  but  it 
is  true  in  the  main.  The  average  content  of  sulfur  in  Illinois 
coals  is  from  3  to  4  per  cent.,  with  an  occasional  output  as  high  as 
6  or  even  7  per  cent.  In  the  southern  and  southeastern  field, 
however,  as  in  Franklin,  Williamson,  Saline  and  Jackson  counties 
the  sulphur  content  will  average  from  1  to  2  per  cent. 

Volatile  Matter. — The  organic  matter  of  coal  when  heated 
above  350  or  400°C.  decomposes  giving  off  combustible  gases 
and,  if  the  temperature  is  continued  to  a  bright-red  heat,  there 
remains,  in  addition  to  the  ash,  the  fixed  carbon  or  coking  con- 
stituent of  the  coal.  The  volatile  matter  is  of  significance 
largely  by  reason  of  the  fact  that  this  part  of  the  combustible 
substance  has  a  tendency  to  escape  into  the  flue  spaces  before  com- 
plete combustion  has  been  effected.  With  mechanical  stokers 
and  modern  equipment,  this  would  not  occur  and,  conse- 
quently, the  matter  of  high-  or  low-volatile  matter  is  of  less  sig- 
nificance than  formerly.  In  domestic  appliances,  however,  this 
is  not  the  case,  and  larger  losses  occur  in  the  process  of  com- 
bustion. For  such  uses,  therefore,  higher  efficiency  will  be  ob- 
tained from  coals  with  less  volatile  matter  and  a  higher 
percentage  of  fixed  carbon. 

Fixed  Carbon. — The  fixed  carbon  represents  the  amount  of 
combustible  matter  which  remains  behind  for  complete  combus- 
tion in  the  fire  box.  Its  value,  therefore,  depends  upon  the  form 
of  appliance  in  which  the  coal  is  burned.  The  fixed  carbon  plus 
the  ash  represents  approximately  the  coke  content  that  might  be 
expected  from  the  original  coal.  It  should  be  noted  that  fixed 
carbon  is  a  product  of  the  destructive  distillation  of  the  organic 
matter  of  the  coal,  and  is  not  a  constituent  of  the  coal  in  its 
natural  form  at  all.  Moreover,  the  fixed  carbon  carries  with 
it  as  adsorbed  or  chemically  combined  material  small  percentages 
of  nitrogen,  sulphur,  hydrogen  and  possibly  oxygen. 


CHAPTER  V 
UNIT  COAL 

Definitions. — In  fuel  literature  three  terms  have  come  into 
use: 

1.  Combustible. 

2.  Ash  and  water-free  substance. 

3.  Pure  coal. 

These  terms  are  synonymous  and  are  intended  to  represent  the 
active  or  actual  coal  substance.  The  heat  value,  for  example, 
when  referred  to  the  combustible  matter,  is  found  by  dividing 
the  heat  value  as  obtained  on  the  wet  coal  by  1.00  —  (sum  of 
moisture  and  ash  as  weighed).  From  the  previous  discussion, 
it  is  evident  that  in  coals  of  the  Illinois  type  with  their  high-ash 
content  there  will  be  a  very  considerable  error  unless  we  make  use 
of  a  corrected  ash,  hence  there  has  been  suggested1  another  term, 
that  of  "Unit  Coal,"  which  is  intended  to  stand  for  the  pure  or 
actual  coal  substance  as  derived  from  taking  into  consideration 
the  corrected  ash.  In  other  words  the  attempt  is  made  to 
differentiate  between  the  non-coal  substance  and  the  coal  itself. 
The  latter  is  a  fairly  constant  material  in  its  heat  producing  prop- 
erty and  general  makeup  of  its  chemical  compounds.  The 
non-coal  substance  on  the  contrary  is  made  up  of  a  number  of  in- 
gredients, more  or  less  adventitious,  and  varying  both  in  actual 
amount  present  and  also  in  composition  as  they  pass  through  the 
processes  of  analytical  determination.  For  example  the  iron 
pyrites  which  is  a  large  factor  in  the  non-coal  material  is  weighed 
out  with  the  coal  in  the  form  of  Fe$2.  After  burning  to  ash  it 
becomes  Fe203  and  the  application  of  a  correction  factor  to  the 
ash  as  weighed  is  necessary  if  we  wish  to  revert  to  the  original 
condition  of  the  ash.  Similarly,  the  shale  or  clayey  constituents 
have  in  chemical  combination,  a  certain  amount  of  water  which 
is  not  driven  off  by  drying  at  steam  temperature,  but  is  delivered 
1  Univ.  of  111.  Eng.  Exp.  Sta.,  Bull  37. 

31 


32  FUEL.  GAS,  WATER  AND  LUBRICATION 

at  a  red  heat  in  the  process  of  ashing.  Here  again,  if  we  wish  to 
obtain  a  factor  for  the  true  ash  or  non-coal  substance  we  must 
apply  another  correction  to  account  for  this  loss  of  combined 
water.  An  expression,  therefore,  for  the  non-coal  substance 
has  been  adopted  as  follows: 

Non-coal  =  Moisture  +  Ash-as-weighed  +  f  S  +  0.08  (Ash-as- 
weighed  -  V-S). 

Derivation  of  the  Formula  for  Unit  Coal. — The  factors  in  this 
expression  are  derived  as  follows:  In  the  ash  as  weighed  the 
FeS2  of  the  original  coal  has  burned  to  Fe203.  In  this  combi- 
nation the  atomic  ratio  of  the  oxygen  to  the  total  sulphur 
which  it  replaces,  that  is  Fe2O3,  2(FeS2)  :  :  48  :  128  or  3  :  8. 
This  means  that  oxygen  has  combined  with  the  iron  to  the  extent 
of  three-eighths  of  the  weight  of  the  original  sulphur.  Hence,  the 
ash  as  weighed  may  be  corrected  or  brought  to  its  original  form 
so  far  as  the  FeS2  is  concerned  by  adding  five-eighths  of  the  weight 
of  the  sulphur  present  in  the  coal.  The  assumption  here  is  that  all 
of  the  sulphur  is  present  as  FeS2.  Since  there  is  always  a  certain 
amount  of  sulphur  present  in  organic  combination,  the  above  fac- 
tor carries  with  it  a  small  error  which  is  referred  to  later  in 
the  discussion. 

Again  the  ratio  of  iron  to  sulphur  in  iron  pyrites  (FeS2)  is 
56:64;  that  is,  the  amount  of  iron  present  is  seven-eighths  of  the 
weight  of  the  sulphur.  The  combined  iron  and  oxygen,  therefore 
weighed  as  Fe203  are  equivalent  to  f  +  f  or  V  of  the  sulphur 
present.  Hence,  the  expression  (Ash-as-weighed  —  -^S)  repre- 
sents the  ash  with  the  pyritic  iron  or  the  resulting  oxide  Fe2O3 
removed.  Therefore,  since  the  original  FeS2  from  which  it 
comes  has  no  combined  water,  it  is  subtracted  before  applying 
the  correction  constant  of  0.08.  This  8  per  cent  is  a  constant  and 
represents  the  water  of  hydration  for  the  clayey  constituents 
which  we  wish  to  restore  to  the  ash  as  in  its  original  form. 

The  above  formula  for  " non-coal"  becomes  therefore  the 
expression  for  the  true  coal  or  "Unit  Coal"  in  percentage  values 
as  follows: 

Unit  Coal  =  1.00  -  [(Water  +  Ash-as-weighed  +  fS)  + 
0.08  (Ash-as-weighed  -  -Y-S)]. 

By  clearing  of  fractions  and  bringing  to  its  simplest  form,  this 
expression  becomes: 


UNIT  COAL  33 

Unit  Coal  =  1.00  -  (W  +  1.08A  +  fiS)  in  which  W  is  the 
percentage  of  water,  A  is  the  percentage  of  ash-as-weighed,  and 
S  is  the  sulphur  content. 

In  this  last  formula,  two  corrections  are  made  for  iron  pyrites 
by  assuming  all  of  the  sulphur  to  be  in  pyritic  form  ;  the  first  cor- 
rection f  S  gives  a  correction  which  has  an  error  of  the  plus  order. 
Similarly  the  second  correction,  -^-S,  has  a  similar  error,  larger 
than  the  first,  and  as  these  are  of  opposite  signs,  they  tend  to 
neutralize  each  other.  However,  the  error  involved  in  *•£•&  is 
greater  than  in  the  factor  fS.  There  will  thus  have  been  sub- 
tracted too  large  an  increment  in  reducing  to  the  final  form  of 
}^S.  We  shall  approach  nearer  the  truth  therefore  by  slightly 
increasing  this  value.  It  will  have  the  added  advantage  also  of 
convenience  in  calculating  if  we  increase  the  factor  to  f-J  or 


The  formula  as  finally  devised  becomes: 

Unit  Coal  =  1.00  -  (W  +  1.08  A  +  f|S) 

Correction  Constant  for  Water  of  Composition.  —  Brief  refer- 
ence should  here  be  made  to  the  correction  constant  of  0.08 
added  to  the  ash  as  weighed  or,  as  it  appears  in  the  final  formula, 
I.  OS  A.  The  need  of  such  a  correction  is  of  course  more  obvious 
to  those  working  with  coals  of  the  mid-continental  area  where  the 
ash  is  shaley  material  which  carries  always  a  certain  percentage 
of  water  of  composition  not  removable  by  oven  drying,  but  only 
discharged  at  a  red  heat.  The  value  0.08  was  chosen  after  a 
number  of  determinations  upon  the  shales  connected  with  the 
Illinois  coal  measures  of  the  content  of  combined  water. 

Accuracy  of  the  Constants  Employed  for  Correction  of  Ash.  — 
It  is  evident  that  the  factors  adopted  for  correction  of  the  ash  are 
largely  empirical.  The  ultimate  evidence  as  to  their  suitability 
therefore  will  be  cumulative,  resulting  from  an  extended  appli- 
cation. Such  evidence  will  appear  under  subsequent  headings. 
One  of  the  more  direct  methods  for  testing  their  accuracy  is 
given  here  as  follows  : 

Suppose  a  sample  of  coal,  ground  to  about  10-mesh,  is  sepa- 
rated by  the  usual  methods  into  "sink"  and  "float"  material. 
A  solution  of  zinc  chloride  is  made  up  to  a  specific  gravity  slightly 
under  that  of  the  coal.  By  stirring  the  coal  sample  into  such  a 
solution,  usually  1.35  sp.  gr.,  the  heavier  particles,  containing 


34 


FUEL,  GAS,  WATER  AND  LUBRICATION 


the  larger  part  of  the  ash,  "sink"  to  the  bottom,  and  the  particles 
with  lower  ash  " float."  In  this  manner  a  coal  sample  may  be 
resolved  into  two  parts,  one  having  a  high  ash,  and  the  other 
having  a  low  ash.  If  now  we  obtain  the  calorific  value  on  the 
unit-coal  basis,  the  factors  when  applied  to  the  high-ash  material, 
if  correctly  devised,  will  show  a  substantial  agreement  with  the 
heat  values  for  the  unit  coal  of  the  low-ash  division.  On  the  other 
hand,  if  these  factors  are  wrong,  their  application  to  the  high-ash 
values  will  accentuate  the  error  and  show  a  wide  discrepancy  in 
the  heat  values  for  the  unit  coal  of  each  subdivision.  Again, 
if  we  can  produce  a  wide  variation  in  the  sulfur  content,  the 
calculation  for  unit  coal,  which  of  course  is  sulphur-free,  will 
accentuate  any  error  in  the  correction  factors  adopted  for  that 
constituent.  In  this  manner,  both  the  correction  values  for 
sulphur,  to  account  for  iron  pyrites,  and  for  the  hydration  of  the 
high-shale  content  of  the  ash,  are  given  a  test.  Reference  to 
Table  V  will  show  the  results  obtained  on  a  number  of  " float" 
and  "sink"  samples  as  thus  described. 

Other  evidence  in  detail  has  accumulated  in  verification  of  the 
constancy  of  unit-coal  values,  especially  for  a  given  mine  or 

TABLE  V. — UNIT-COAL  HEAT  VALUES  FOB  FLOAT  AND  SINK  SAMPLES 


No. 

Description  of  samp] 

e 

Moist- 
ure 

Ash 

Sul- 
phur 

B.t.u. 
as  re- 
ceived 

B.t.u. 
for  unit 
coal 

Dif- 
fer- 
ence 

1 

Grundy  County,  111.  ...   < 

Float 
Sink 

0.0 
0.0 

4.57 
21.99 

1.44 
5.00 

13,475 
10,733 

14,217 
14,262 

45 

Pi 

Williamson  County,  111. 

'  Float 
Sink 

0.0 
0.0 

4.08 
17.75 

0.99 
1.15 

13,942 
11,766 

14,615 
14,599 

16 

3 

Williamson  County,  111. 

Float 
Sink 

0.0 
0.0 

4.34 

18.28 

1.07 
1.37 

13,970 
11,731 

14,690 
14,667 

23 

4 

Sangamon  County,  111.  . 

Float 
Sink 

0.0 
0.0 

6.12 
11.66 

3.20 
5.99 

13,300 
12,356 

14,340 
14,331 

9 

5 

Sangamon  County,  111..    • 

Float 
Sink 

0.0 
0.0 

8.13 
18.21 

2.95 
4.25 

13,045 
11,478 

14,392 
14,442 

50 

6 

Peoria  County,  111  - 

Float 
Sink 

2.17 
1.70 

8.26 
35.08 

2.61 
5.88 

12,612 
8,426 

14,268 
14,221 

47 

7 

South  Africa 

Float 

1.63 

6.06 

1.38 

13,793 

15,065 

28 

^Sink 

1.66 

18.94 

2.28 

11,680 

15,093 

3 

South  Africa  .  .  • 

Float 

2.07 

8.88 

0.87 

12,989 

14,779 

20 

Sink 

1.82 

15.24 

1.80 

11,847 

14,799 

9 

South  Africa  < 

Float 

1.70 

11.12 

0.72 

12,628 

14,638 

72 

Sink 

1.87 

20.20 

0.75 

11,092 

14,566 

UNIT  COAL  35 

county  or  region,  and  thus,  also  incidentally  affording  a  consist- 
ent index  of  subclassifications  which  cannot  be  obtained  by  any 
other  method.  The  following  references  contain  a  considerable 
amount  of  such  data  together  with  illustrative  applications  to 
which  unit  coal  values  may  be  applied: 

PARR,  S.  W.  and  WHEELER,  W.  F.,  Unit  coal  and  the  composition  of 
Coal  Ash:  Univ.  of  111.  Eng.  Exp.  Sta.,  Bull  37  (1909). 

PARR,  S.  W.,  Purchase  and  sale  of  Illinois  coal  on  specification:  111.  State 
Geol.  Surv.,  Bull.  29  (1914). 

PARR,  S.  W.,  Chemical  study  of  Illinois  coals:  Cooperative  investigations, 
I.  S.  G.  S.,  Univ.  of  111.  Eng.  Exp.  Sta.,  and  U.  S.  Bureau  of  Mines,  Bull.  3 
(1916). 


CHAPTER  VI 
CALORIMETRIC  MEASUREMENTS 

Definitions. — Heat  values  are  expressed  in  two  ways — as  Cal- 
ories and  as  British  thermal  units.  Only  the  large  Calorie  is 
made  use  of  in  fuel  reference  and  it  represents  the  amount  of 
heat  necessary  to  raise  1  kilo  of  water  through  1°C.  The  full 
expression  is,  therefore,  Calories  per  kilo  or  kilo-Calories. 

The  British  thermal  unit  represents  the  amount  of  heat  neces- 
sary to  raise  1  Ib.  of  water  through  1°F.  The  full  expression, 
therefore,  would  be  B.t.u.  per  pound. 

Since  the  Centigrade  degree  is  |  or  1.8  times  as  great  as  the 
Fahrenheit  degree,  and  the  kilo  is  2.2046  times  the  pound,  it 
follows  that  1  Cal.  would  be  the  equivalent  in  Fahrenheit  degrees 
of  1.8  X  2.2046  or  3.968  B.t.u.  However,  the  comparison 
between  units  as  thus  developed  is  not  a  comparison  between 
values  as  made  use  of  in  the  case  of  fuels  for  the  reason  that  the 
arbitrary  amount  of  coal  to  which  reference  is  made  in  both  cases 
is  an  amount  of  coal  equal  to  the  unit  of  water  taken,  that  is  a  kilo 
of  coal  to  a  kilo  of  water,  a  pound  of  coal  to  the  pound  of  water. 
For  this  reason,  therefore,  the  rise  in  temperature  in  each  case  is 
the  same.  That  is,  a  pound  of  coal  will  raise  the  temperature  of  a 
pound  of  water  through  as  many  degrees  as  a  kilo  of  coal  will  raise 
a  kilo  of  water,  or  a  ton  of  coal  a  ton  of  water,  etc.  The  difference 
in  heat  values  as  expressed  by  these  two  methods,  therefore,  is 
simply  the  difference  in  the  thermometric  readings.  A  reading 
taken  by  the  Fahrenheit  scale  will  be  f  or  1.8  times  as  great  as 
the  reading  taken  by  the  Centigrade  scale.  Therefore,  to 
change  fuel  values  expressed  in  Calories  per  kilo  to  B.t.u.  per 
pound,  multiply  by  1.8. 

This  relation  of  1  :  1.8,  it  should  be  observed,  refers  to  solid  or 
liquid  fuels  only,  that  is,  where  the  ratio  of  fuel  to  total  water  is 
that  of  equivalent  quantities.  Fortunately,  this  relationship 
applies  to  Continental  values  as  well  as  English  and  American, 

36 


CALORIMETRIC  MEASUREMENTS  37 

so  that  the  transfer  from  Calories  to  B.t.u.  is  simple  and  uni- 
versally applicable  for  such  material.  The  matter  is  quite  differ- 
ent, however,  in  the  case  of  gaseous  fuels  where  the  unit  quantity 
of  reference  is  not  the  same.  For  example,  the  B.t.u.  value  of  a 
cubic  foot  of  gas  must  be  divided  by  3.968  to  find  the  equivalent 
in  calories  per  cubic  foot.  Then  since  there  are  35.314  cu.  ft.  in 
1  cubic  meter,  the  expression  for  transferring  gas  values  from 
B.t.u.  per  cubic  foot  to  calories  per  cubic  meter  would  be 

35  314 
B.t.u.  per  cu.  ft.  X  0  ^Q    =  Cal.  per  cubic  meter 


B.t.u.  per  cu.  ft.  X  8.8997  =  Cal.  per  cubic  meter. 
Heat  Values  by  Calculation. — Heat  values  may  be  determined 
from  the  ultimate  analysis  by  Dulong's  formula,  which  assumes 
that  the  heat  comes  from  the  combustion  of  carbon,  hydrogen, 
and  sulphur.     The  usual  values  for  these  constituents  are 

Carbon  =    8,080  Cal.  or  14,544  B.t.u. 

Hydrogen  =  34,500  Cal.  or  62,100  B.t.u. 

Sulphur  =    2,500  Cal.  or    4,500  B.t.u. 

Expressed  in  the  latter  set  of  values,  therefore,  Dulong's 
formula  becomes 

14,544C  +  62,100  (u  -   g  j  +  4,500S  =  B.t.u. 

\  / 

In  this  formula  the  expression  (H  —  — )    represents  what  is 

o 

termed  the  available  hydrogen;  that  is,  the  amount  left  after 
subtracting  the  equivalent  hydrogen  needed  to  unite  with  the 
oxygen  present  to  form  water,  2:16  or  JO. 

Presumably  such  calculated  values  would  be  in  close  agreement 
with  indicated  values  by  means  of  a  carefully  operated  instru- 
ment. This  is  true  for  certain  regions  but  not  for  others.  The 
divergence  is  more  pronounced  in  coals  of  the  Illinois  region  than 
in  the  coals  of  the  eastern  United  States.  "In  view  of  the  pos- 
sible presence  of  calcium  carbonate  and  the  consequent  error  in 
the  ash  determination  for  many  Illinois  coals,  it  is  evident  that  a 
direct  variable  in  such  cases  enters  into  the  value  for  oxygen  and 
consequently  for  the  available  hydrogen,  which  would  thereby 
result  in  a  discrepancy  as  between  the  indicated  and  the  calcu- 
lated calorific  values.  Moreover,  a  high  percentage  of  oxygen 


38  FUEL,  GAS,  WATER  AND  LUBRICATION 

in  combination  evidently  may  be  responsible  for  variations  of 
quite  a  different  character,  as,  for  example,  a  different  distribu- 
tion of  such  oxygen  in  a  manner  not  altogether  correctly  covered 

by  the  expression  g-,  or  in  the  ultimate  form  of  water.     There 

seems  to  be,  therefore,  numerous  reasons  why  a  calculated 
calorific  value  by  use  of  Dulong's  formula  is  of  little  value  for 
coals  of  this  type."1 

The  Berthier  Test. — The  Berthier  test  is  based  on  the  property 
of  carbon  to  reduce  the  oxide  of  lead  at  a  red  heat.  The  higher 
the  percentage  of  combustible  present,  the  larger  the  button. 
One  gram  of  coal  is  mixed  with  60  grams  of  litharge  and  heated 
to  redness  in  a  crucible.  The  weight  of  the  button  thus  obtained 
is  multiplied  by  421.  The  product  represents  theoretically  the 
reducing  power  of  the  carbon  in  terms  of  British  thermal  units. 
It  should  be  increased  by  about  the  value  of  the  available  hydro- 
gen present.  In  Illinois  coals  this  does  not  vary  widely  from 
3.5  per  cent,  making  the  addition  of  a  constant  necessary  of 
about  2,000  B.t.u.  The  results  thus  obtained  may  vary  from 
the  truth  by  300  to  800  units,  or  from  3  to  8  per  cent.  The 
method  has  historical  rather  than  practical  interest. 

Lewis  Thompson  Calorimeter. — This  is  a  bell  shaped  receptacle 
for  submerging  in  water  and  containing  within  the  bell  a 
cartridge  having  a  mixture  of  coal,  2  grams;  with  22  grams  of  a 
mixture  of  potassium  nitrate  3  parts,  and  potassium  chlorate,  1 
part.2  According  to  Schorer-Kestner3  this  apparatus  normally 
gives  results  that  are  in  error  by  about  15  per  cent.  This  appa- 
ratus also  dates  back  to  a  time  when  a  mere  approximation  to 
the  correct  values  was  all  that  seemed  to  be  demanded  by  fuel 
users.  At  the  present  time  a  degree  of  exactness  is  required 
which  was  impossible  with  either  of  the  methods  just  described. 

Other  Types. — There  are  two  types  of  calorimeters  using 
oxygen  as  a  medium  for  carrying  on  the  combustion — those  in 
which  the  oxygen  is  maintained  at  atmospheric  pressure  and 

1  PARR,  S.  W.,  111.  State  Geol.  Surv.,  Yearbook,  p.  236,  1909. 

Also,  PORTER  and  OVITZ,  Bureau  of  Mines,  Bull.  1,  p.  28-29. 

2  For  details  of  the  apparatus  see  "Fuel,  Water  and  Gas  Analysis,"  by 
KERSHAW. 

3  Jour.  Soc.  Chem.  Ind.,  vol.  7,  p.  869. 


CALORIMETRIC  MEASUREMENTS 


39 


those  using  oxygen  under  approximately  25  atmospheres.  The 
first  condition  is  referred  to  as  that  of  constant  pressure  and  the 
second  as  that  of  constant  volume. 

Of  the  first  type,  the  best  known  perhaps  are  Fischer's,  Car- 
penter's, W.  Thompson's,  etc.,  which  conduct  a  current  of 
oxygen  into  a  chamber  containing  the  fuel.  The  chief  disad- 
vantage results  from  imperfect  combustion,  especially  with  high- 
ash  coals  due  to  fusion  of  the  ash  with  consequent  enclosure  and 
protection  of  the  carbonaceous  matter  from  further  oxidation. 

Oxygen  Bomb  Calorimeter. — Calorimeters  using  oxygen  at 
approximately  25  atmospheres  pressure  are  designated  as  of  the 
Berthelot  or  Mahler  type  from  the  names  of 
the  investigators  who  were  pioneers  in  their 
development  and  use.  A  typical  bomb  of 
this  type  is  shown  in  Fig.  12.  A  carefully 
weighed  amount  of  coal  is  held  in  a  capsule 
within  the  bomb.  The  bomb  after  charging  is 
placed  in  the  can,  Fig.  36  and  a  known  quantity 
of  water  added.  After  placing  in  the  insu- 
lated receptacle,  and  putting  in  place  the  cover, 
an  equalization  of  the  temperature  is  brought 
about  by  rotation  of  the  stirrer.  After  igni- 
tion and  equalization  again  of  the  temperature, 
the  factors  are  at  hand  for  deriving  the  heat 
value  of  the  coal  according  to  the  formula : 

-D  ,  rise  X  total  water 

B.t.u.  =  -       .  ,  .     , 

weight  of  coal 

For  example,  if  1  gram  of  coal  were  taken  and  the  total  water  used, 
including  the  water  equivalent  of  the  apparatus,  were  2,400 
grams,  then  for  a  rise  of  say,  4°F.  the  heat  value  would  be  9,600 
B.t.u.  By  this  procedure,  therefore,  may  be  found  the  rise  in 
temperature  which  a  given  weight  of  coal  will  impart  to  an 
equivalent  weight  of  water,  thus  satisfying  the  conditions  of  the 
definition  of  the  British  thermal  units  per  pound  of  fuel. 

Also  as  already  noted  under  "  Definitions,"  in  this  same 
example,  if  a  Centigrade  scale  were  used  the  rise  in  temperature 
would  be  2.222°  which  by  introducing  into  the  computation 
would  give  5,333  CaL,  the  temperature  rise  in  Centigrade 


FIG. 


12. — Oxygen 
bomb. 


40  FUEL,  GAS,  WATER  AND  LUBRICATION 

degrees  that  a  given  amount  of  this  fuel  would  impart  to  an 
equivalent  weight  of  water. 

Note  especially,  that  in  all  the  discussions  pertaining  to  the 
oxygen  bomb  it  is  assumed  that  the  Centigrade  scale  is  used  and 
the  final  values  are  in  Calories.  If,  finally,  the  values  are  wanted 
in  B.t.u.  the  factor  1.8  is  applied. 

Correction  for  Radiation. — If  the  system  containing  the  bomb 
and  measured  quantity  of  water  is  operated  at  a  temperature 
above  or  below  that  of  the  room,  a  gain  or  loss  of  heat  will  result 
due  to  radiation.  This  may  be  corrected  for  in  a  very  accurate 
manner  by  taking  the  thermometer  readings  each  minute  for  a 
preliminary  period  of  5  min.  and  also  for  a  final  period  of  5  min., 
with  an  intervening  period  usually  of  about  5  min.  The  rates 
of  radiation  change  thus  obtained  are  incorporated  into  a  formula 
covering  the  period  of  combustion  and  equalization  of  the  system 
as  follows: 

The  rate  of  rise  for  the  preliminary  period  is  ri  and  for  the 
final  period  is  r2.  The  time  readings  are  indicated  as  a,  b  and 
c.  At  a  is  noted  the  time  of  ignition.  At  c  the  time  of  final  or 
maximum  reading,  and  at  b  the  time  when  the  thermometer  has 
reached  the  point  of  rise  equivalent  to  six-tenths  of  the  total 
between  a  and  b.  In  computing,  the  rate  ri  is  multiplied  by  the 
time  b  —  a,  in  minutes  and  tenths  of  a  minute,  and  this  product 
is  added  to  the  temperature  reading  at  a.  Similarly  the  rate  r2 
is  multiplied  by  the  time  interval  c  —  b  and  the  product  added 
to  the  time  c.  Assuming  that  the  thermometer  corrections  for 
stem  and  setting  have  already  been  made,  the  difference  of  the 
two  thermometer  readings  thus  corrected  give  the  total  rise  of 
temperature  due  to  combustion.  If  the  temperature  was  falling 
at  the  time  a,  then  the  system  is  losing  instead  of  gaining  heat, 
and  the  correction  is  minus  instead  of  plus,  a  reduction  of  the 
subtrahend  operating  as  a  plus  correction.  Similarly,  if  the 
temperature  is  rising  at  the  time  c,  the  system  is  gaining  heat 
and  the  correction  for  the  period  c  —  b  should  be  minus  instead 
of  plus.  In  the  case  of  coals  where  the  approximate  total  rise  is 
unknown,  and  hence  the  time  reading  b  at  the  six-tenths  point 
uncertain,  it  is  only  necessary  to  take  readings  at  15-sec.  intervals 
for  approximately  2  min.  These  observations  will  enable  one 
to  readily  locate  the  six-tenth  point  when  all  the  readings  are 


CALORIMETRIC  MEASUREMENTS  41 

completed.  This  formula  has  been  devised  by  Dr.  Dickinson 
of  the  U.  S.  Bureau  of  Standards,1  and  has  been  adopted  by  the 
joint  committee  of  the  American  Chemical  Society  and  the 
American  Society  for  Testing  Materials  on  Standard  Methods  for 
Coal  Analysis.2  It  is  exceedingly  convenient  and  accurate,  and 
in  the  report  of  the  committee,  entirely  replaces  the  very 
elaborate  and  tedious  method  of  Pfaundler.3 


FIG.  13. — A  calorimeter  of  the  adiabatic  type. 

Adiabatic  Insulation. — To  avoid  the  necessity  of  accounting  for 
radiation  losses  and  eliminating  possible  errors,  as  also  to  simplify 
the  matter  of  readings  and  calculations,  various  methods  of 
insulation  involving  adiabatic  conditions  have  been  developed. 

1  U.  S.  Bureau  of.  Standards,  Scientific  Paper,  230. 

2  Am.  Soc.  for  Testing  Mat.,  "Standards,"  p.  576,  1916. 

3  For  an  excellent  presentation  of  the  Pfaundler  formula  see  WHITE'S 
"  Gas  and  Fuel  Analysis,"  2d  ed.,  p.  268,  1920,  or  1st  ed.,  p.  224,  1913. 


42  FUEL,  GAS,  WATER  AND  LUBRICATION 

To  be  thoroughly  effective  these  methods  should  involve  com- 


Fio.  14. — The  adiabatic  calorimeter  showing  details  of  construction. 

plete  control  over  the  temperature  of  the  insulating  part  of  the 
apparatus  in  such  a  way  as  to  cause  the  temperature  to  rise 


CALORIMETRIC  MEASUREMENTS  43 

coordinately  with  that  of  the  combustion  system.  Such  instru- 
ments are  designated  as  adiabatic  calorimeters.  Their  greater 
convenience  of  operation  and  possibilities  of  extreme  accuracy 
are  apparent. 

In  the  instrument  here  illustrated,  Fig.  14,  the  water  is  cir- 
culated by  means  of  the  stirrer  R,  which  includes  also  a  small 
turbine  for  directing  a  portion  of  the  water  upward  in  G,  and  thus 
through  the  lid  C.  In  this  manner  the  jacketing  water  is  dis- 
tributed on  all  sides,  above  and  below  the  container  F  with  the 
bomb  B. 

Correction  for  Acids. — One  other  condition  exists  in  the  use 
of  the  Mahler  type  of  calorimeter  which  requires  consideration. 
Because  of  the  use  of  pure  oxygen  at  a  high  pressure  and  tempera- 
ture, certain  reactions  take  place  which  do  not  occur  in  the 
ordinary  process  of  combustion.  For  example,,  a  small  amount 
of  residual  air  present  upon  closing  the  instrument  has  free 
nitrogen  which  under  the  conditions  of  combustion  is  partially 
oxidized  to  N2O5  or  with  the  moisture  present  in  the  bomb  it 
becomes  HN03.  Similarly  the  nitrogen  of  the  coal  burns  to  a 
greater  or  less  extent  to  HNO3.  The  sulphur  in  the  coal  which 
under  ordinary  conditions  of  combustion  burns  to  SO2,  in  the 
calorimeter  burns  to  SOs  or  with  the  moisture  present,  to  H2SO4. 
These  two  highly  corroding  acids  make  it  necessary  to  protect 
the  interior  surface  of  the  bomb.  This  is  accomplished  by  use 
of  an  enamel,  by  a  spun  lining  of  gold  or  platinum,  or  by  con- 
structing the  bomb  of  an  acid  resisting  alloy  equivalent  in  that 
respect  to  gold  or  platinum.  Where  such  a  precaution  is  dis- 
regarded, as  for  example,  if  the  enamel  type  of  protection  becomes 
cracked  and  scaled  off  or  if  a  lining  of  spun  metal  such  as  nickel 
is  employed,  the  solvent  property  of  the  acids  becomes  active. 
There  are  two  sources  of  error  which  result  from  such  conditions 
— one  is  the  heat  of  solution  resulting  from  the  chemical  action. 
This  of  course  should  not  be  credited  to  the  heat  content  of  the 
coal.  It  would  be  relatively  small  in  amount,  probably  not 
exceeding  5  to  10  cal.  The  other  is  the  masking  of  the  amount 
of  free  acid  which  thus  escapes  measurement  and  would  be 
uncorrected  for.  In  high-sulphur  coals  of  the  Illinois  type  the 
error  from  this  source  may  be  of  considerable  moment,  frequently 
equaling  or  even  exceeding  100  cal. 


44  FUEL,  GAS,  WATER  AND  LUBRICATION 

The  amount  of  free  acid  in  the  bomb  washings  is  first  deter- 
mined by  means  of  a  standard  solution  of  Na2C03  made  up  of 
such  a  strength  that  each  cubic  centimeter  represents  1  cal. 
The  heat  of  formation  for  HN03  is  1,035  cal.  per  gram  of  nitrogen. 
The  reaction  for  neutralization  is: 

2HNO3  +-  Na2C03  =  2NaN03  +  H2C03 
28N  :  106  Na2C03 
N  :  3.786  Na2CO3 

That  is  1  gram  N,  burning  to  HN03  and  representing  1,035  cal., 
requires  3.786  grams  Na2C03.  One  calorie  requires  0.003658 
gram  of  Na2CO3  or  3.658  grams  per  liter  in  which  1  cc.  would 
represent  1  cal. 

In  the  calculation  thus  far  it  has  been  assumed  that  all  of  the 
acid  present  was  HNO3.  The  H2S04  must  be  taken  into  the 
account. 

When  sulphur  burns  to  SO3  aqua,  it  develops  approximately 
4,450  cal.  per  gram  of  S.  In  ordinary  combustion  the  burning 
to  S02  generates  only  2,250  cal.  per  gram.  The  excess  heat 
resulting  from  conditions  within  the  bomb  would  be  represented 
by  4,450  -  2,250  =  2,200  cal.  per  gram  of  S.  But  the  titration 
for  1  gram  of  N  as  HN03  would  represent  only  seven-eighths  of  a 
gram  of  S  as  H2S04.  This  is  evident  from  the  ratio : 

2HN03  :  H2S04  :  2Na2C03 
28  :32 

Hence,  the  titration  as  HNO3  for  the  H2S04  would  be  only  seven- 
eighths  of  the  heat  to  be  credited  to  the  sulphur  per  gram.  This 
means  that  seven-eighths  of  the  1,035  cal.  or  900  cal.  per  gram  of 
sulphur  have  been  corrected  for.  Hence,  2,200  -  900  or  1,300 
would  represent  the  additional  correction  required  for  1  gram 
of  sulphur  or  13  cal.  per  0.01  gram  of  sulphur,  equivalent  to  13 
cal.  additional  for  each  per  cent  of  sulphur  present  in  the  coal. 

It  is  at  once  obvious  that  the  acid  correction  is  a  matter  of 
some  moment.  Illinois  coals  having  from  3  to  5  per  cent  of 
sulphur  will  show  a  titration  of  from  35  to  50  c.c.  of  the  standard 
alkali  representing  an  equivalent  number  of  calories  reckoned  as 
HNO3,  aqua.  A  coal  having  4  per  cent  of  sulphur  would  have 


CALORIMETRIC  MEASUREMENTS  45 

that  correction  augmented  by  4  X  13  or  52  cal.,  or  a  correction 
on  account  of  the  two  acids  of  from  85  to  125  cal.  or  from  150 
to  225  B.t.u. 

In  the  above  considerations  all  of  the  sulphur  present  is 
supposed  to  be  in  the  form  of  organic  sulphur  or  FeS2,  and  to 
burn  to  H2S04.  Badly  weathered  coal  may  have  an  appreciable 
amount  of  the  FeS2  weathered  to  Fe2S04,  but  in  open  bins'this 
will  be  practically  eliminated  by  leaching. 

For  complete  combustion  to  H2S04  it  is  also  well  to  note  that 
sufficient  nitrogen  must  be  present  to  furnish  a  proper  amount  of 
N2C>5  as  catalyzer  for  the  sulphur.1 

The  correction  in  calories  for  the  acids  formed  together  with 
the  correction  for  fuse-wire  are  subtracted  from  the  total  observed 
calories. 

Correction  for  Fuse  Wire. — The  coal  in  the  bomb  is  ignited  by 
a  fuse  of  iron  wire,  Brown  and  Sharpe  gage  No.  34,  and  7  cm.  in 
length.  The  weight  of  wire  burned  is  determined  with  sufficient 
accuracy  by  measuring  the  length  of  the  unburned  wire.  The 
weight  of  the  total  length  will  be  sufficiently  constant  so  that 
repeated  weighings  are  not  necessary.  The  total  observed  cal- 
ories are  corrected  by  subtracting  for  the  iron  at  the  rate  of  1,600 
cal.  per  gram  of  wire  burned. 

The  Peroxide  Calorimeter. — Another  type  of  calorimeter,  Fig. 
30,  is  extensively  used  in  which  the  coal  is  mixed  with  a  chemical 
which  will  supply  the  oxygen  to  complete  the  combustion  within 
a  closed  cartridge.  This  method  is  more  conveniently  available 
perhaps  for  technical  work.  The  procedure  is  described  under 
the  directions  for  calorimetric  measurements  (Part  II,  p.  149). 
With  this  instrument  the  Fahrenheit  scale  is  more  commonly 
employed. 

The  principles  involved  are  as  follows:  Sodium  peroxide,  Na202, 
when  mixed  with  coal  in  suitable  proportion  and  ignited,  may  be 
made  to  burn  or  react  through  an  appreciable  period  of  time  but, 
instead  of  the  formation  of  gaseous  products  as  in  the  ordinary 
process  of  combustion,  the  C02  and  H20  unite  with  the  chemical 
employed  to  form  the  carbonate  and  hydrate  of  sodium,  which 
are  solids.  These  reactions  shown  in  detail  are  as  follows: 

1  Jour.  Ind.  and  Eng.  Chem.,  vol.  16,  p.  812,  1914. 


46  FUEL,  GAS,  WATER  AND  LUBRICATION 

,  .  f  2Na2O2  +  C     =  2Na20  +  C02 

I  2Na20  +  C02  =  Na2C03  +  Na20 

( MI          f  Na202  +  H2     =  Na2O  +  H20 
1  Na2O  +  H2O    =  2NaOH 

Of  the  total  heat  developed  in  the  reactions  under  (a),  0.73 
represents  the  heat  of  combination  between  the  carbon  and 
oxygen.  Also,  under  (b),  the  total  heat  of  the  reactions  is  made 
up  of  73  parts,  which  includes  the  heat  formed  by  the  union  of 
the  hydrogen  with  the  oxygen,  and  27  parts,  which  represents 
the  secondary  reaction  or  combination  of  the  water  with  the 
chemical.  This  distribution  of  heat  values  is  fortunate  for  the 
reason  that  we  may  make  the  factor  0.73  a  constant  which  repre- 
sents the  part  of  the  total  heat  to  be  taken  as  the  equivalent  of 
the  heat  of  ordinary  combustion.  Other  corrections  must  be 
applied  to  the  indicated  rise  in  temperature  as  detailed  in  the 
method  of  operation  (Part  II,  p.  155).  A  brief  discussion  having 
reference  to  the  reason  for  applying  the  corrections  is  here 
given. 

First. — The  ignition  is  effected  by  an  electrically  heated  fuse 
wire.  The  amount  of  heat  introduced  by  the  electric  current 
and  combustion  of  the  wire  is  found  to  be  0.005°F. 

Second. — The  combination  of  the  ash  with  the  sodium  peroxide, 
forming  in  the  main  sodium  and  aluminum  silicates,  is  attended 
with  a  slight  increment  of  temperature  which  is  found  by  direct 
experiment  to  amount  to  0.005°F.  for  each  per  cent  of  ash  present 
in  the  fuel. 

Third. — The  sulphur  in  ordinary  combustion  burns  to  sulphur 
dioxide,  S02,  while  in  the  reaction  with  the  chemical  the  ultimate 
result  is  Na2S04.  The  difference  in  the  heat  resulting  from  the 
two  reactions  should  be  subtracted  from  the  indicated  tempera- 
ture. The  amount  of  the  correction  is  determined  by  burning 
pure  iron  pyrites,  FeS2,  in  the  apparatus  and  comparing  the  heat 
evolved  with  the  accepted  heat  value  for  the  combustion  of  an 
equivalent  amount  of  sulphur  to  S02.2  The  difference  is  found 

1  The  complete  reactions  involved  are  probably  expressed  by  the  equation 
Na2O2  +  Na2O  +  O  +  4H  =  4NaOH.     See  The  constants  of  the  Parr 
calorimeter,  Jour.  Am.  Chem.  Soc.,  vol.  19,  p.  1616. 

2  Loc.  cit.,  p.  1620. 


CALORIMETRIC  MEASUREMENTS  47 

to  be  equivalent  to  0.010°F.  for  each  per  cent  of  sulphur  present 
in  the  coal. 

Fourth. — For  the  more  perfect  combustion  of  all  types  of  coal 
and  also  for  supplying  the  seemingly  needed  free  or  nascent  oxy- 
gen for  the  combustion  of  the  hydrogen,  an  accelerator  is  used  in 
conjunction  with  the  sodium  peroxide,  preferably  chlorate  of 
potash,  finely  pulverized  and  dry.  The  heat  of  decomposition 
of  this  material  plus  the  recombination  of  the  free  oxygen  with 
the  Na20  resulting  from  the  reactions  with  carbon  amount  to 
0.270°F.  per  gram  of  KC103  used. 

The  indicated  rise  of  temperature  is,  therefore,  first  corrected 
for  the  several  components  enumerated,  and  the  corrected  rise  is 
used  in  the  formula: 

r  X  w  X  0.73 
B.t.u.  =          -gr- 

in  which  r  is  the  corrected  rise  in  temperature,  w  is  the  water 
equivalent  of  the  water  and  metal  of  the  apparatus,  2,123.3 
grams,  and  C  is  the  weight  of  coal  taken,  0.5  gram.  This  will 
give  us  the  rise  in  degrees  Fahrenheit  or  B.t.u.  which  an  equal 
weight  of  coal  will  yield  upon  combustion,  provided  the  actual 
heat  of  combustion  is  imparted  to  an  equivalent  of  water. 

Since,  in  the  above  formula  the  factors  for  w,  C,  and  the  con- 
stant 0.73  occur  in  all  cases,  their  resulting  value  becomes  a 
constant  equal  to  3,100.  Thus, 

2,123.3  X  0.73 

~05~  3'1C 

Gross  and  Net  Heat  Values. — In  all  of  the  calorimetric 
considerations  thus  far  the  results  as ,  computed  give  the  gross 
values,  that  is,  with  the  products  of  combustion  reduced  in 
temperature  to  approximately  that  of  the  surrounding  air,  20 
to  35°C.  This  means  that  the  water  formed  in  the  reactions 
has  given  up  to  the  system  its  latent  heat  of  vaporization.  The 
weight  of  water  is  (hydrogen  X  9)  and  the  weight  of  water 
X  0.600  represents  the  latent  heat  of  vaporization  in  calories 
to  be  subtracted  from  the  observed  calories.  The  remainder  is 
the  net  heat  value. 

There  is  not  a  little  disagreement  as  to  which  value,  the  gross 
or  net,  is  the  more  important.  In  ordinary  steam  generating 


48  FUEL,  GAS,  WATER  AND  LUBRICATION 

installations  where  the  flue  gases  are  delivered  above  the  point 
of  condensation,  the  net  values  would  seem  to  be  required.  The 
engineer  however  in  developing  his  heat  balance  takes  into 
account  the  heat  of  vaporization  of  all  of  the  moisture,  whether 
free  or  formed  in  the  reactions,  and  it  is  simpler  therefore  to 
charge  all  such  heat  to  the  total  or  gross  heat  of  the  coal.  It  is 
desirable  on  this  account  that  he  be  furnished  the  hydrogen  factor 
as  one  of  the  constituents  of  the  chemical  analysis.  This  requires 
an  ultimate  analysis  of  the  coal,  or  a  simplified  procedure  as 
described  in  the  following  chapter. 

Partial  bibliography  relating  to  coal  calorimetry. 

LORD  and  SOMEBMEIER,  Ohio  State  Geol.  Surv.,  4  th  ser.,  Bull.  9,  p.  320. 
ATWATER,  Jour.  Am.  Chem.  Soc.,  vol.  25,  p.  659. 
PARR,  S.  W.,  Jour.  Am.  Chem.  Soc.,  vol.  29,  p.  1606. 
PARR,  S.  W.,  Jour.  Ind.  and  Eng.  Chem.,  vol.  1,  No.  9,  p.  673. 
FRIES,  J.  A.,  Investigations  in  the  use  of  the  bomb  calorimeter:  U.  S.  Dept. 
Ag.,  Bull.  94,  1907. 

SOMERMEIER,  E.  E.,  "Coal,  Its  Composition,  Analysis,  etc.,"  1912. 
WHITE,  A.  H.,  "Technical  Gas  and  Fuel  Analysis,"  1914. 
DICKINSON,  H.  C.,  U.  S.  Bureau  of  Standards,  Scientific  Paper,  No.  230. 
REGISTER,  S.  A.,  The  function  of  nitrogen  in  the  bomb  calorimeter:  Jour. 
Ind.  and  Eng.  Chem.,  vol.  6,  p.  812. 

Report  of  the  Committee  E-4,  Methods  of  sampling  and  analysis  of  coal : 
Proc.  Am.  Soc.  for  Testing  Mat.,  vol.  14,   p.  444,  1914;  Jour.  Ind.  and 
Eng.    Chem.,    vol.   5,  p.   517,    1913.     Also  Am.  Soc.  for  Testing  Mat.. 
"Standards,"  p.  550,  1916. 


CHAPTER  VII 
ULTIMATE  ANALYSIS 

Total  Carbon. — As  a  substitute  for  the  elaborate  and  not 
always  satisfactory  ultimate  analysis  of  coal  the  following  method 
will  be  found  both  convenient  and  accurate,  fully  meeting  the 
requirements  of  the  engineer  in  boiler-testing  computations. 

The  carbon  content  of  coal  may  be  readily  determined  from 
the  fusion  with  sodium  peroxide  resulting  from  the  calorimetric 
determinations  making  use  of  that  process.  Combustions  with 
Na20'2  may  also  be  made  in  a  simple  piece  of  apparatus  devised 
for  that  purpose  and  not  involving  the  elaborations  necessary 
where  temperature  readings  are  involved.  Figure  40  shows 
the  apparatus  for  obtaining  the  fusions. 

After  the  reaction  is  completed,  the  fusion  cup  is  transferred 
to  a  beaker,  the  contents  dissolved  and  transferred  with  thorough 
washing  and  as  little  contact  with  air  as  possible  to  the  apparatus 
shown  in  Fig.  43.  Details  of  manipulation  are  given  in  Part  II. 
The  results  enable  us  to  derive  with  a  high  degree  of  accuracy 
the  factor  for  carbon. 

Derivation  of  Hydrogen  by  Calculation.— In  the  calculations 
for  deriving  a  heat  balance,  the  engineer  requires  the  factor  for 
the  total  hydrogen  in  the  coal  used.  The  hydrogen  present  is 
considered  as  combined  in  two  different  ways.  In  one,  the 
hydrogen  is  " disposable "  or  " available"  for  combustion. 
In  the  other  it. is  supposed  to  be  joined  with  oxygen  to  form  H20 
and  when  thus  combined  is  not  available  for  the  production  of 
heat.  The  available  hydrogen  may  be  derived  as  follows:  If 
we  let  C  represent  the  percentage  of  total  carbon,  then  14,544C 
will  equal  the  heat  value  for  that  constituent.  To  this  add 
the  heat  value  of  the  sulphur  present,  5,OOOS.  The  remainder  of 
the  heat  is  due  to  the  combustion  of  hydrogen.  Hence,  with  a 
value  for  hydrogen  of  62,100  the  percentage  of  available  hydrogen 
H,  will  be  represented  by  the  expression: 

_  B.t.u.  -  (14,544C  +  5,OOOS) 
62,100 

4  49 


50  FUEL,  GAS,  WATER  AND  LUBRICATION 

The  hydrogen  not  available  or  considered  to  be  in  combination 
with  oxygen  is  estimated  as  one-eighth  of  the  oxygen  or  -^  as  in 

o 

Dulong's  formula.  There  is  required,  therefore,  the  percentage 
of  oxygen  and  this  is  determined  by  difference.  That  is,  if  we 
subtract  from  100  the  values  for  ash,  sulphur,  total  carbon,  avail- 
able hydrogen,  and  nitrogen,  the  difference  will  be  the  non- 
available  hydrogen  and  oxygen  present  in  the  ratio  of  H2  :  O. 
Hence  one-ninth  of  this  difference  is  H2  and  eight-ninths  is  the 
oxygen  percentage.  That  is,  the  percentage  of  chemically 
combined  water  is  represented  by  the  formula: 

H20  =  100  -  (A  +  S  +  C  +  available  H  +  N) 
The  only  undetermined  factor  in  the  above  expression  is  that 
for  nitrogen.  It  may  be  determined  directly  by  the  Kjeldahl 
method,  or,  for  purposes  of  calculating  a  heat  balance  it  is  quite 
sufficiently  accurate  to  assume  a  value  of  1  per  cent  for  nitrogen, 
since  the  amount  present  in  bituminous  coals  varies  only  within 
relatively  narrow  limits,  say  from  0.75  to  1.50  per  cent.  These 
calculations  can  also  be  made  to  good  advantage  by  basing  the 
factors  upon  the  pure  combustible  or  "Unit  Coal'7  described  in 
Chapter  V.  The  final  results  however  are  not  essentially 
different.  It  is  especially  to  be  noted  that  in  this  treatise,  all 
reference  to  oxygen  and  hydrogen  in  coal  is  on  the  assumption 
that  the  free  moisture  is  separately  determined  by  drying  at 
105°C.  and  reported  as  moisture.  The  hydrogen  and  oxygen  of 
the  free  moisture  therefore  do  not  appear  as  constituents  of  the 
coal. 


CHAPTER  VIII 


CLASSIFICATION  OF  COALS 

Frazer's  Classification.1 — The  classification  of  coal  in  common 
use  was  outlined  by  Frazer  in  1877  and  was  based  on  his  study 
of  the  coals  of  Pennsylvania.  A  wider  knowledge  of  the  char- 
acter of  western  and  mid-continental  deposits  calls  for  the  addition 
of  a  few  subdivisions.  In  tabular  form  the  following  classifi- 
cation based  on  that  of  Frazer  most  nearly  approaches  everyday 
usage : 

Anthracites,  Volatile  matter,  below  5  percent 


COALS 


Semi-anthracites, 

Semi-bituminous, 
(Pocahontas) 


Bituminous 


Eastern, 


Mid-Con- 
tinental, 


Vol.,  5-10  per  cent 
Vol.,  15-22  per  cent 


Vol.,  25-35  per  cent 
Vein  Moist.,  2-4  per  cent 


Vol.,  35-45  per  cent 

Vein  Moist.,  6-17  per  cent 


Black  Lignites, 
or  Sub-bituminous 


/  Vol.,  35-45  per  cent 
1  Vein  Moist.,  17-20  per  cent 
j  Vol.,  25-45  per  cent 
Brown  Lignites,  \  Vein  Moist.,  20-25  per  cent 

Numerous  systems  of  classification  have  been  proposed,  but 
none  has  been  received  with  sufficient  unanimity  to  warrant  its 
general  adoption.  In  the  main,  they  are  based  on  certain  ratios 
which  have  come  to  be  designated  by  technical  terms  as  follows : 

Fuel  Ratio. — A  term  originally  proposed  by  Johnston,  and 
modified  by  Frazer  is  represented  by  the  fixed  carbon  divided  by 
Fixed  C 


the  volatile  matter, 


Since  this  ratio  is  highest  in  the 


Vol.  M. 

1  FRAZER,  PERSIFER,  JR.,  Trans.  Min.  Eng.,  vol.  6,  p.  430,  1878. 

51 


52  FUEL,  GAS,  WATER  AND  LUBRICATION 

anthracites  and  semi-anthracites,  and  lowest  in  the  lignites,  it 
serves  in  a  general  way  as  an  indication  of  the  type  of  coal  as 
well  as  its  behavior  under  conditions  of  combustion. 

Carbon-hydrogen  Ratio. — This  term  was  proposed  by  Camp- 
bell and  represents  the  percentage  of  total  carbon,  divided  by  the 

T  C 
percentage  of  total  hydrogen,     '     •     These  factors  are  obtained 

by  ultimate  analysis  and  are  not  usually  available.  Unfortu- 
nately also  the  hydrogen  factor  used  by  Campbell  was  the  total 
hydrogen  of  the  coal  and  also  of  the  free  moisture  which  may  have 
happened  to  be  present  at  the  time  of  analysis.  As  this  constitu- 
ent is  variable  and  does  not  govern  either  the  geological  or  chemi- 
cal characteristics  of  the  coal  it  should  not  be  a  contributing 
element  in  the  carbon-hydrogen  ratio. 

The  free  moisture  as  it  occurs  in  the  coal  vein  does  have  how- 
ever with  comparatively  few  exceptions  a  real  significance  as  an 
accompaniment  of  the  various  types  of  coal.  This  factor  how- 
ever begins  to  vary  as  soon  as  the  coal  is  broken  out  of  the  seam. 
The  topic  is  one  of  geological  interest  however,  and  is  well  set 
forth  in  Campbell's  later  discussion  on  classification,  which  also 
defines  the  main  coal  types  in  terms  which  will  doubtless  be 
universally  adopted.1 

The  Carbon  Ratio. — This  represents  the  volatile  carbon  (that 
is,  the  carbon  joined  with  hydrogen  or  other  elements  to  admit 
of  its  assuming  a  volatile  form)  divided  by  the  total  carbon  con- 
tent of  the  coal  and  this  multiplied  by  100  gives  directly  the 
per  cent  the  volatile  carbon  is  of  the  total  carbon. 

The  advantage  of  any  ratio,  making  use  of  the  actual  fuel 
constituents,  is  the  fact  that  it  remains  the  same  whether  the 
moisture  and  ash  are  present  or  absent,  thus  eliminating  some 
of  the  most  serious  variables  inherent  in  many  of  the  proposed 
schemes  of  classification. 

Classification  by  Heat  Values. — By  eliminating  the  variables, 
such  as  moisture,  ash  and  all  adventitious  material,  it  is  evident 
that  the  heat  value  for  the  residual  substance  would  be  modified 
by  the  inherent  variations  of  the  pure  coal  constituents,  that  is, 
the  carbon,  hydrogen  and  oxygen  present.  Obviously  therefore, 

1  Professional  Paper  100-4,  by  M.  R.  CAMPBELL,  1917. 


CLASSIFICATION  OF  COALS  53 

this  leads  us  to  a  consideration  of  the  heat  values  for  unit  coal  as 
a  basis  of  classification.  Such  values  will  be  found  to  give  very 
consistent  indications  of  the  type  variations. 

Derivation  of  Heat  Values  for  Unit  Coal.  —  It  is  obvious  that  if 
the  heat  value  of  the  unit  coal  is  constant  within  narrow  limits 
for  a  given  mine  or  region  we  may  if  such  unit  values  are  known, 
reverse  the  calculation,  making  use  of  any  known  or  assigned 
values  for  moisture,  ash  and  sulphur,  and  so  determine  by  calcula- 
tion the  heat  value  of  the  commercial  product  for  that  particular 
mine  or  region  for  which  the  unit  coal  value  is  a  constant.  We 
shall  need  to  discuss  in  the  first  place,  therefore,  the  method  of 
calculating  unit  coal  values. 

From  our  previous  discussion  of  the  formula  which  has  been 
developed  to  represent  the  percentage  of  unit  coal,  it  is  readily  seen 
that  the  expression  for  deriving  the  heat  value  for  that  substance 
would  be  as  follows:  Using  W  for  water,  A  for  ash,  and  S  for 
sulphur.  For  coals  with  values  given  on  the  "  as-received  "  or 
"wet"  basis: 

,  TT  .,  ^     .       Indicated  (Wet)  B.t.u.  -  5,OOOS 
:  T,00  -  (W  +  1.08A  +  22/40S)- 

For  coals  with  values  given  on  the  "dry"  or  moisture-free  basis: 
,  TT   .,  0     ,       Indicated  (dry)  B.t.u.  -  5,OOOS 


1.00  -  (1.08A  + 

The  expression  5,OOOS  has  been  used  as  indicating  the  heat  due 
to  the  combustion  of  sulphur,  for  the  reason  that  the  value  4,500S 
as  used  in  Dulong's  formula  represents  the  heat  of  combustion 
for  pure  sulphur,  while  the  heat  of  combustion  of  sulphur  in  the 
form  of  pyrites,  :JFeS2,  combines  also  the  heat  of  formation  of 
iron  oxide,  Fe203.  It  is  the  resultant  value,  therefore,  of  the 
several  reactions  involved  that  is  desired. 

According  to  the  direct  tests  by  Somermeier,1  in  the  combustion 
of  coal  with  known  weights  of  iron  pyrites,  the  indicated  heat 
per  gram  of  sulphur  so  combined  is  4,957  cal.  In  calculating 
heat  values,  the  correction  introduced  for  the  combinations 
resulting  from  calorimeter  reactions  as  compared  with  open-air 
combustion  is  2,042  cal.  per  gram  of  pyritic  sulphur,  hence  4,957 
-  2,042  or  2,915  cal.  (5,247  B.t.u.)  represents  the  heat  due  to 

1  Jour.  Am.  Chem.  Soc.,  vol.  26,  p.  566. 


54  FUEL,  GAS,  WATER  AND  LUBRICATION 

burning  one  gram  of  sulphur  in  pyritic  form  instead  of  2,250  cal. 
(4,050  B.t.u.),  the  amount  which  would  be  credited  to  sulphur  in 
the  free  condition.  A  strict  application  of  these  values,  there- 
fore, would  call  for  a  correction  of  5,247S,  as  representing  the 
heat  to  be  subtracted  for  the  sulphur.  This,  however,  would  imply 
that  all  of  the  sulphur  is  in  the  pyritic  form.  Since  a  certain  por- 
tion of  the  sulphur  is  always  present  in  organic  or  other  form  of  less 
heat-producing  capacity,  it  is  deemed  more  nearly  correct  to  use 
an  even  factor  of  5,000  as  representing  the  heat  to  be  credited 
to  unit  amounts  of  the  total  sulphur  present. 

The  adaptability  of  this  formula  for  determining  the  percentage 
of  the  pure  coal  substance  has  been  fully  set  forth  in  Chapter  V. 
The  data  there  given,  using  the  calorific  values  as  evidence  of 
constancy  of  composition  for  given  areas,  may  naturally  be 
interpreted  in  terms  of  classification  or  demarcation  of  types. 
This  point  may  be  graphically  represented  by  reference  to 
Fig.  15. 

In  this  illustration  three  types  of  coal  are  shown  with  the 
relative  amounts  of  each  constituent  indicated  by  appropriate 
areas.  In  that  part  of  the  pure  coal  substance  designated  as 
volatile  matter  the  oxygen  compounds  are  shown  by  the  cross- 
hatched  portions.  Evidently  the  extent  of  these  areas,  being 
calculated  to  the  fully  oxygenated  or  " inert"  basis,  furnish  a 
very  pronounced  influence  upon  the  calorific  value  of  the  pure 
coal  or  "Unit"  material.  This  basis  of  classification  is  made 
use  of  in  the  discussion  and  references  which  follow. 

By  computing  the  heat  values  as  derived  by  this  formula  for 
solid  fuels  throughout  the  United  States,  as  published  by  the 
United  States  Geological  Survey,  the  Ohio  State  Survey,  and 
the  Illinois  Geological  Survey,  we  have  in  tabular  form,  giving 
the  extremes  for  each  general  fuel  type,  the  following: 

TABLE  VI. — CLASSIFICATION  OF  FUEL  TYPES  BY  HEAT  VALUES  FOR  UNIT 
COAL  OR  ACTUAL  ORGANIC  SUBSTANCE 

B.  T.  U. 

Cellulose  and  wood 6, 500  to    7,800 

Peat 7,800  to  11,500 

Lignite,  brown 11,500  to  13,000 

Lignite,  black,  or  subbituminous  coal 13,000  to  14,000 

Bituminous  coal  (mid-continental  field) 14,000  to  15,000 

Bituminous  coal  (eastern  field) 15,000  to  16,000 

Semi-anthracite  and  semi-bituminous 15,500  to  16,000 

Anthracite 15,000  to  15,500 


CLASSIFICATION  OF  COALS 


55 


u 


56  FUEL,  GAS,  WATER  AND  LUBRICATION 

This  study  has  been  carried  still  further  by  the  Illinois  State 
Geological  Survey,  and  the  extremes  have  been  derived  for  the 
various  seams  as  worked  throughout  the  coal  area  of  the  state. 

It  is  to  be  recalled  that  the  geologists  recognize  16  coal  seams 
for  Illinois,  counting  from  the  bottom  of  the  coal  measures 
upward.  Only  seven  of  these  seams  are  of  workable  thickness. 
The  numbering  1  to  7  follows  the  geological  order,  and  not  that 
used  in  some  localities,  as  at  La  Salle,  Bloomington,  etc.,  where 
the  number  of  the  seam  is  that  which  resulted  from  the  order  of 
their  development  from  the  surface  downward. 

Composition  of  Illinois  Coals. — A  recent  survey  carried  on  by 
the  Illinois  State  Geological  Survey  in  cooperation  with  the 
U.  S.  Bureau  of  Mines  covered  all  of  the  coal  producing  counties 
of  Illinois  and  included  something  over  100  mines.  The  analyti- 
cal values  for  the  coals  from  these  mines  have  been  averaged 
for  the  various  counties  and  are  assembled  in  Table  VII.  Where 
mining  operations  are  carried  on  from  different  seams  in  the  same 
county,  the  average  for  the  single  seam  indicated  is  given  sepa- 
rately and  not  for  the  county  as  a  whole.  Also,  for  the  reason 
that  some  of  the  seams  vary  widely  in  character  from  north  to 
south,  the  letters  N,  C,  or  S  are  occasionally  used  to  designate 
the  general  region  from  which  the  samples  are  taken,  namely  the 
north,  central,  or  southern  zones.  Similarly,  since  in  some 
rather  restricted  localities  a  marked  alteration  in  the  seam  occurs 
from  east  to  west,  the  letters  E  and  W  are  used  as  in  Perry 
County,  the  letter  E  signifies,  for  seam  No.  6,  east  and  W  west  of 
the  DuQuoin  anticline. 

A  brief  bibliography  of  discussions  upon  coal  classification  is  given  as 
follows : 

JOHNSON,  W.  R.,  Report  to  United  States  Government  on  "American  Coals," 
1844. 

URE'S  "Dictionary,"  1845. 

FRAZEB,  PERSIPER,  JR.,  Trans.  Min.  Eng.,  vol.  6,  p.  430,  1878. 

WATT'S  "Dictionary  of  Chemistry,"  vol.  1,  p.  1032. 

ROGERS,  H.  D.,  Report  to  English  Government,  vol.  2,  part  2,  p.  983. 

U.  S.  Geol.  Surv.  Professional  Paper,  No.  48. 


CLASSIFICATION  OF  COALS 


57 


TABLE  VII. — AVERAGE  ANALYTICAL  AND  HEAT  VALUES  FOR  PRODUCING 

COUNTIES  IN  ILLINOIS 
(Compiled  from  Bull  No.  29  111.  State  Geol.  Survey) 


Table 
no. 

County 

Geo- 
logical 
seam 

Total 
mois- 
ture 

Vola- 
tile 
matter 

Fixed 
carbon 

Ash 

Sul- 
phur 

Carbon 
diox- 
ide 

B.t.u. 

"Unit 
coal" 

1 

Bureau 

2N 

16.27 

38.35 

38.00    7.38 

2.93 

0.89 

10,883 

Dry 

45.80 

45.39    8.81 

3.50 

1.40 

12,997 

14,477 

2 

Christian 

1C 

11.31 

38.89 

40.941   8.86 

2.35 

0.43 

11,602 

Dry 

43.85 

46.16!   9.99 

2.65 

0.48 

13,081 

14,717 

3 

Clinton 

6S 

12.62 

37.08 

40.10  10.20 

3.90 

0.66 

10,796 

Dry 

42.45 

45.90 

11.67 

4.4B 

0.75 

12,355 

14,290 

4 

Franklin 

6S 

9.04 

34.62 

47.78 

8.56 

1.45 

0.44 

11,837 

Dry 

38.06 

52.53 

9.41 

1.59 

0.48 

13,013 

14,538 

5 

Fulton 

5N 

16.16 

36.27 

37.09  10.48 

3.14 

1.33 

10,363 

Dry 

43.26 

44.24  12.50 

3.74 

1.59 

12,361 

14,416 

6 

Gallatin 

5S 

4.30 

35.93 

49.08 

10.69 

3.79 

0.24 

12,616 

Dry 

37.54 

51.29 

11.17 

3.96 

0.25 

13  ,  183 

15,109 

7 

Gallatin 

6S 

7.54 

34.96 

45.68 

11.82 

4.34 

0.23 

11,916 

Dry 

37.81 

49.41 

12.78 

4.70 

0.25 

12,888 

15,136 

8 

Grundy 

2N 

17.28 

38.48 

39.02 

5.27 

2.33 

0.83 

11.113 

Dry 

46.49 

47.14 

6.37 

2.82 

1.00 

13,426 

14,496 

9 

Jackson 

2S 

9.28 

33.98 

51.02 

5.72 

1.29 

0.29 

12,488 

Dry 

37.46 

56.24 

6.  3D 

1.42 

0.32 

13,765 

14,818 

10 

Jackson 

6S 

8.96 

34.44 

46.40 

10.20 

2.65 

0.40 

11,609 

Dry 

37.83 

50.97 

11.20 

2.91 

0.44 

12,751 

14,608 

11 

La  Salle 

2C 

15.70 

39.54 

36.17 

8.59 

3.48 

0.96 

10,731 

Dry 

46.91 

42.89 

10.20 

4.12 

1.15 

12,728 

14,444 

12 

La  Salle 

5C 

14.76 

41.33 

34.26!   9.65 

3.38    0.61 

10,692 

Dry 

48.49 

40.  19111.  32 

3.97 

0.71 

12,543 

14,397 

13 

La  Salle 

7C 

13.56 

40.87 

37.80!   7.77 

3.68 

0.17 

11,347 

Dry 

47.28 

43.73j   8.99 

4.26 

0.20 

13,127 

14,685 

14 

Logan 

5C 

14.20 

37.19 

37.44)11.37 

3.34 

1.42 

10,490 

Dry 

43.35 

43.  40,13.  25 

3.89 

1.66 

12,226 

14,400 

15 

McLean 

5C 

13.32 

38.00 

36.2l|l2.27 

3.73 

1  20 

10,580 

Dry 

43.84 

41.78114.38 

4.30 

1.39 

12,206 

14,604 

16 

McLean 

2C 

11.26 

42.21 

37.73    8.80 

3.03 

0.98 

11,566 

Dry 

47.57 

42.52 

9.91 

3.41 

1.10 

13,034 

14,714 

17 

Macon 

5C 

14.15 

36.68 

38.83 

10.34 

3.57 

0.52 

10,661 

Dry 

42.73 

45.23  12.04 

4.16 

0.60 

12,418 

14,419 

18 

Macoupin 

6C 

13.88 

38.20 

37.75  10.17 

4.31 

0.34 

10,657 

Dry 

44.36 

43.83  11.81 

5.00 

0.39 

12,375 

14,349 

19 

Madison 

6S 

13.47 

38.59 

38.03    9.91 

4.22 

0.42 

10,760 

Dry 

44.60 

43.95 

11.45 

4.88 

0.49 

12.435 

14,370 

20 

Marshall 

2N 

15.10 

39.06 

38.68 

7.16 

2.79 

0.48 

11.315 

Dry 

46.01 

45.56 

8.43 

3.28 

0.56 

13,327 

14,796 

21 

Marion 

6S 

10.79 

37.53 

40.46 

11.22 

3  96 

0.45 

11,069 

Dry 

42.07 

45.35 

12.58 

4.44 

0.51 

12.408 

14,511 

22 

Menard 

5C 

17.33 

35  .  88 

38.62 

8.17 

3.44 

0.50 

10,499 

Dry 

43.40 

46.72 

9.88 

4.16 

0.60 

12,700 

14,478 

23 

Mercer 

1W 

15.58 

39.17 

35  .  80 

9.45 

4.69 

0.53 

10,673 

Dry 

46.40 

42.41 

11.19 

5.55 

0.63 

12,643  14,546 

24 

Montgomery 

6C 

14.15 

36.88 

39.14 

9.83 

3.84 

0.70 

10,642 

Dry 

42.96 

45.59 

11.45 

4.47 

0.83 

12,396  14,290 

25 

Moultrie 

6C 

6.83 

39.15 

42.32 

11.70 

4.02 

0.57 

11,877 

Dry 

42.02 

45.42 

12.56 

4.31 

0.61 

12,748  14,882 

26 

Peoria 

5C 

14.96 

36.65 

36.99 

11.40 

3.26 

1.50 

10,506 

Dry 

43.10 

43.49 

13.40 

3.83 

1.77 

12,354  14,614 

27 

Perry 

6C 

9.92 

32.72 

46.97 

10.39 

0.92 

0.25 

11,335 

Dry 

36.81 

52.15 

11.53 

1.02 

0.28 

12,583  14,407 

28 

Perry 

6W 

11.00 

36.75 

41.97 

10.28 

3.36 

0.56 

11,087 

Dry 

41.29 

47.16 

11.55 

3.78 

0.63 

12,457  14,359 

29 

Randolph 

6S 

11.13 

37.28 

40.14 

11.45 

4.24 

0.58 

10,855 

Dry 

41.95 

45.17 

12.89 

4.77 

0.65 

12,214il4,351 

30 

Saline 

5S 

6.92 

35.44 

49.06 

8.58 

3.76 

0.39 

12,314] 

Dry 

38.08 

52.70 

9.22 

4.04 

0.42 

13,229  14.794 

31 

Sangamon 

5C 

14.35 

37.30 

37.57 

10.78 

4.16 

0.59 

10,555 

Dry 

43.55 

43.86 

12.59 

4.86 

0.69 

12,323 

14,415 

32 

St.  Clair 

6S 

11.25 

39.57 

38.39 

10.79 

3.99 

0.63 

11,028 

Dry 

44.59 

43.26 

12.15 

4.50 

0.71 

12,426 

14,457 

33 

Tazewell 

5C 

14.38 

37.74 

38.23 

9.66 

3.10 

1.20 

10,809 

Dry 

44.08 

44.65 

11.28 

3.62 

1.40 

12,624 

14,496 

34 

Vermilion 

6C 

14.45 

35.88 

40.33 

9.34 

2.55 

0.75 

10,920 

Dry 

41.94 

47.14 

10.92 

2.98 

0.88 

12,764 

14,575 

35 

Vermilion 

7C 

12.99 

38.28 

38.75 

9.98 

2.93 

0.56 

11,143 

Dry 

44.00 

44.53 

11.47 

3.37 

0.64 

12.807 

14,740 

36 

Williamson 

6S 

9.31 

33.38 

48.90 

8.41 

1.54 

0.36 

11,913 

Dry 

36.81 

53.92 

9.27 

1.70 

0.40 

13.136il4.655 

I 

58  FUEL,  GAS,  WATER  AND  LUBRICATION 

PARR,  S.  W.,  Jour.  Am.  Chem.  Soc.,  vol.  28,  p.  1425. 
CAMPBELL,  M.  R.,  A.  I.  M.  E.,  vol.  36,  p.  324. 
GROUT,  F.  F.,  "Economic  Geology,"  p.  226,  1907. 
WHITE,  DAVID,  U.  S.  Geol.  Surv.  Bull  No.  382. 
CAMPBELL,  U.  S.  Geol.  Surv.,  Professional  Paper  100-A. 


CHAPTER  IX 

COAL    CONTRACTS1 

Introduction. — Present-day  tendencies  relating  to  the  purchase 
of  coal  under  specification  are  reflected  in  the  following  quota- 
tions: 

When  a  proper  sample  of  the  coal  is  secured,  the  chemical 
analyses  and  calorimeter  determinations  for  B.t.u.  are  a  better 
guide  to  the  value  of  the  coal  than  are  one  or  two  boiler  tests  for 
the  same  purpose.2 

The  purchase  of  coal  under  specification  is  as  advantageous  as 
a  definite  understanding  regarding  the  quality  and  other  features 
of  any  other  product,  or  of  a  building  operation  or  engineering 
project.  The  man  who  buys  under  specification  gets  what  he 
pays  for  and  pays  for  what  he  gets.3 

The  heating  power  expressed  in  British  thermal  units  per  pound 
is  the  most  direct  measure  of  the  value  of  coal.  Contracts  made 
on  what  is  termed  the  " heat-unit  basis"  provide  therefore  that 
the  amount  of  money  paid  shall  be  in  direct  proportion  to  the 
number  of  heat  units  delivered.  It  is  evident  that  the  number 
of  heat  units  varies  inversely  with  the  quantity  of  ash  and  mois- 
ture. That  the  bidder  should  be  thoroughly  familiar  with  these 
factors  in  their  application  to  the  coal  which  he  proposes  to 
furnish  is  self-evident.  A  thorough  understanding  of  the 
methods  of  awarding  contracts  is  essential  to  the  dealer  who  pro- 
poses to  enter  bids  on  a  competitive  basis.  Similarly  the  pur- 
chaser must  not  only  be  able  to  formulate  his  own  contracts  but 
also  to  check  up  the  various  bids  in  a  way  that  will  enable  him 
to  determine  their  reasonableness  and  likelihood  of  proper  fulfill- 
ment. Specifications  for  the  purchase  of  coal  have  passed 
through  an  extended  process  of  development.  It  may  be  that 

1  PARR,  S.  W.,  Adapted  from  111.  State  Geol.  Surv.,  Bull  29,  1914. 

2  "The  Purchase  of  Coal,"  The  Arthur  D.  Little,  Inc.,  Laboratory  of 
Engineering  Chemistry,  pp.  10-11,  1909. 

3  POPE,  G.  S.,  Purchase  of  coal  by  the  government  under  specifications: 
U.  S.  Geol.  Surv.,  Bull.  428,  p.  10,  1910. 

59 


60 


FUEL,  GAS,  WATER  AND  LUBRICATION 


no  one  method  is  even  now  applicable  in  all  regions  or  under  all 
conditions.  The  discussion  here  presented  is  based  mainly  on 
the  practice  of  the  Board  of  Administration  for  Illinois  in  the 
purchase  of  coal  for  the  State  Institutions.  It  is  closely  related 
also  to  the  procedure  employed  by  the  United  States  under  the 
immediate  direction  of  the  Bureau  of  Mines  in  the  purchase  of 
coal  for  government  use. 

Calculation  of  Commercial  Heat  Values  for  Contracting 
Purposes. — From  what  has  already  preceded  in  the  discussion  of 
unit  coal  values  and  the  reliability  of  the  constants  thus 
developed,  it  will  at  once  suggest  the  use  of  such  factors  on  the 
part  of  the  coal  operator  or  dealer  in  formulating  a  proposal  for 
coal  deliveries.  A  brief  resume  and  application  of  this  feature 
will  be  helpful. 

In  Table  VIII  a  few  illustrative  examples  are  given  of  unit 
coal  values.  Complete  tables  covering  all  of  the  producing 
counties  of  the  state  have  recently  been  published1  from  which 
these  figures  have  been  taken: 

TABLE  VIII. — AVERAGE  HEAT  VALUE  FOR  UNIT  COAL  IN  BRITISH  THERMAL 

UNITS  PER  POUND 


No. 

County 

Coal 
bed 

Number  of 
samples  averaged 

Average  —  B.t.u. 
"unit  coal" 

1 

Sangamon  

5 

15 

14,424 

2 
3 

Sangamon  
Macoupin 

6 
6 

5 
6 

14,340 
14,310 

4 

Madison 

18 

14,350 

5 

Vermilion  

6 

19 

14,597 

6 

Vermilion  

7 

9 

14,730 

7 

Williamson  . 

6 

5 

14,750 

The  use  which  can  be  made  of  these  "unit"  values  such  as  are 
shown  in  this  table  may  be  readily  understood  when  it  is 
remembered  that  each  number  represents  material  which  is  100 
per  cent  pure  and  that  for  each  per  cent  of  inert  matter  present, 
such  as  water  and  ash,  there  is  a  corresponding  decrease  in  the 
number  of  heat  units  present.  That  is  to  say,  if  a  coal  has  20 
per  cent  water  and  ash,  then  80  per  cent  of  the  "unit"  value  will 

^ARR,  S.  W.,  Purchase  and  sale  of  Illinois  coals  on  specification:  111. 
State  Geol.  Surv.,:  Bull  29,  1914. 


COAL  CONTRACTS  61 

represent  the  heat  units  present  per  pound  of  coal  as  delivered. 
Indeed,  it  is  possible  by  taking  account  of  certain  refinements 
already  referred  to  such  as  correction  factors  for  sulphur  and  hydra- 
tion  of  the  shaly  constituents,  to  make  a  calculation  which  will 
be  of  quite  sufficient  accuracy  for  basing  bids  and  entering  into 
contracts  involving  a  guarantee  as  to  heat  values.     The  method 
of  calculation  is  exceedingly  simple  and  is  based  on  the  following 
expression: 

Let  A  =  weight  of  ash  per  pound  of  coal. 
Let  S  =  weight  of  sulphur  per  pound  of  coal. 
Then 

"Dry"  B.t.u.  =  "Unit"  B.t.u.  X  [1.00  -  (1.08A  +  0.55S)]  + 
5,OOOS. 

To  illustrate,  take  the  "unit"  value  for  coal  from  Vermilion 
County,  Sample  No.  6  in  Table  VIII.     Suppose  we  wish  to  know 
what  heat  value  can  be  guaranteed  on  deliveries  from  a  mine  of 
this  group  on  the  basis  that  we  can  furnish  material  averaging 
as  the  "dry  coal,"  12  per  cent  ash,  and  3  per  cent  sulphur,  we  will 
have  our  total  non-combustible  material  corrected  by  the  above 
formula  as  follows: 

1.08A.    .    .    .    .    .  ...  .,,.......    12.96 

0.55S   ....   ...   ,  ..    .    .    .    .    ...    .    -      1.65 

Total  .    .    .    ...    .    .    .    .    .    .    .    .    .  14.61 

100%  -  14.61%  =  85.39% 
14,730  X  85.39%  =  12,578 

In  this  calculation  the  sulphur  has  been  neglected.  It  has  a 
small  heat  value  equal  to  5,000  times  the  weight  of  sulphur  present 
or  50  times  the  percentage  number,  thus: 

50  X  3  =  150  units  to  be  added  to  the  above  value,  or 

12,578 
1J>0 

12,728  B.t.u. 

Deliveries  from  this  mine,  therefore,  having  ash,  and  sulphur  as 
indicated  above  can  be  depended  upon  as  carrying  12,728  heat 
units  per  pound  of  "dry"  coal,  and  this  factor  should  be  accurate 
within  100  units  in  12,000  or  less  than  a  variation  of  1  per  cent 
from  values  as  they  would  be  determined  by  direct  reading  from 


62  FUEL,  GAS,  WATER  AND  LUBRICATION 

an  instrument. l  Any  other  set  of  values  for  ash  and  sulph  ur  would 
similarly  admit  of  ready  calculation  and  should  be  used  as  a  basis 
for  calculations  involving  guarantees  of  deliveries  on  a  heat-unit 
basis.  If  the  heat  units  on  the  "wet"  coal  basis  are  desired 
assuming,  for  example,  a  moisture  factor  of  15  per  cent,  the  above 
value  as  derived  for  "dry"  coal  should  be  multiplied  by  0.85, 
that  is,  12,728  B.t.u.  X0.85  =  10,818  B.t.u.  per  pound  of  the  "wet" 
coal,  assuming  a  moisture  factor  of  15  per  cent  as  indicated. 

Significance  of  Heat  Values. — The  cost  of  a  given  lot  of  coal 
must  be  based  upon  the  weight  of  the  material.  The  sample 
taken  should  represent  the  coal  "as  delivered,"  and,  as  already 
emphasized,  moisture  changes  in  the  sample  are  to  be  carefully 
guarded  against.  Variations  in  quality  are  taken  into  account 
by  varying  the  price  per  ton  directly  in  proportion  to  the  number 
of  heat  units  delivered.  In  the  award  of  contracts  and  in  compu- 
tations for  payment,  therefore,  the  calculations  are  based  upon 
the  heat  units  per  pound  in  the  coal  "as  delivered." 

Concerning  the  Ash. — If  there  were  no  other  effect  produced 
by  ash  variations  than  a  corresponding  variation  in  the  heat 
units  then  no  further  account  would  be  taken  of  that  constituent 
since  it  would  be  taken  care  of  in  the  calculations  involving  the 
heat  units.  However,  on  account  of  the  expense  in  handling,  and 
because  of  a  lowering  of  efficiency  resulting  from  excessive  ash, 
an  additional  modification  in  price  is  made  for  this  constituent. 
For  greater  convenience  where  comparisons  are  involved  and  to 
eliminate  the  moisture  variable,  it  is  found  preferable  to  refer  the 
ash  values  to  the  "dry-coal"  basis.  This  involves  the  use  of  a 
double  standard  of  reference;  the  heat  units  are  referred  to  the 
"  wet "  or  "  as-received  "  basis  and  the  ash  is  referred  to  the  "  dry  " 
or  "moisture-free"  basis. 

The  usual  methods  of  applying  the  various  conditions  involved 
are  given  as  follows: 

Bids  and  Awards. — 1.  Bidders  are  required  to  specify  their 
coal  offered  in  terms  of  British  thermal  units  "as-received,"  but 
ash  is  specified  on  the  "dry-coal"  basis.  These  values  become 
the  standards  for  the  coal  of  the  successful  bidder. 

2.  In  order  to  compare  bids,  all  proposals  are  adjusted  to  a 
common  basis.  The  method  used  is  to  merge  all  three  variables 

1  Compare  with  values  found  for  Sample  No.  35,  Table  VII. 


COAL  CONTRACTS 


63 


—ash,  calorific  value,  and  the  price  bid  per  ton — into  one  figure. 
This  figure  will  be  the  cost  in  cents  of  1,000,000  B.t.u.  and  is 
derived  as  follows: 

(a)  All  bids  are  adjusted  to  the  same  ash  percentage  by  select- 
ing as  the  standard  for  comparison  the  proposal  that  offers  coal 
containing  the  highest  percentage  of  ash.  Each  1  per  cent  of 
ash  content  below  that  of  this  standard  will  be  assumed  to  have 
a  positive  value  of  2  cents  per  ton,  and  accordingly  the  price  will 
be  decreased  2  cents,  which  is  approximately  the  amount  of 
premium  allowed  under  the  contract  for  1  per  cent  less  ash  than 
the  standard  established  in  the  contract.  Fractions  of  a  per 
cent  will  be  given  proportional  values.1  The  adjusted  bids  will 
be  figured  to  the  nearest  tenth  of  a  cent. 

(6)  On  the  basis  of  the  adjusted  price,  allowance  will  then  be 
made  for  the  varying  heat  values  by  computing  the  cost  of  1,000,- 
000  B.t.u.  for  each  coal  offered.  This  determination  will  be  made 
by  multiplying  the  guaranteed  B.t.u.  per  pound  by  2,000  and 
dividing  the  product  by  1,000,000.  This  factor  gives  the  guaran- 
teed number  of  million  units  per  ton  of  delivered  coal.  Divid- 
ing the  adjusted  price  as  found  under  (a)  by  this  factor  gives 
the  cost  per  million  heat  units. 

A  convenient  form  for  tabulating  bids  to  indicate  the  various 
factors  entering  into  the  final  computation  of  cost  is  shown  below. 

TABLE  IX. — CONVENIENT  FORM  FOR  TABULATING  BIDS 


Guarantees 

Price  per  ton 
2,000  Ib. 

No. 

Coal  offered 

Ash  in 
"dry 
coal," 

B.t.u. 
"as  received" 

As  bid 

As  ad- 
justed 

cost  in  cents 
per  1,000,000 
B.t.u. 
(b) 

per 

for  ash 

cent 

(a) 

A 

Vermilion  county  screen- 

ings 

17 

10  300 

1  50 

1  50 

7.3 

B 

Sangamon  county  screen- 

ings    .  .                         ... 

16 

10,400 

1.35 

1.33 

6.4 

C 

Williamson    county 

screenings  

14 

12,500 

2.00 

1.94 

7.8 

1  The  actual  amount  of  premium  or  penalty  will  vary  slightly  with  the 
price  as  will  be  seen  under  the  paragraph  on  "Price  and  Payment."  How- 
ever the  use  of  a  common  factor  applied  to  all  bids  will  place  the  various 
estimates  in  their  proper  relative  positions. 


64  FUEL,  GAS,  WATER  AND  LUBRICATION 

Price  and  Payment. — Payment  for  coal  specified  in  the  proposal 
will  be  made  upon  the  basis  of  the  price  therein  named,  which  has 
been  corrected  for  variations  in  heating  value  and  ash  from  the 
standard  specified  in  the  contract,  as  follows: 

(a)  Considering  the  guaranteed  heat  units  on  the  "  as-received  " 
basis,  no  adjustment  in  price  is  made  for  variations  of  2  per  cent 
or  less  in  the  guaranteed  standard.  When  the  variation  in  heat 
units  exceeds  2  per  cent  of  the  guaranteed  standard,  the  adjust- 
ment in  price  will  be  a  proportional  one  and  is  determined  by  the 
following  formula: 

B.t.u.,  delivered   >xl_.j      .  .  -,  £     ^  , 

Tj-r  — ,X  bid  price  =  price  corrected  for  B.t.u. 

B.t.u.,  guaranteed 

The  correction  is  figured  to  the  nearest  tenth  of  a  cent. 

(6)  Considering  the  guaranteed  ash  percentage,  a  tolerance  of 
2  per  cent  above  or  below  the  guaranteed  percentage  of  ash  on 
the  "dry-coal"  basis  is  recognized.  For  variations  greater 
than  2  per  cent  above  or  below  the  standard  guaranteed,  the 
adjustment  in  price  shall  be  determined  as  follows: 

One-half  of  the  discrepancy  in  ash  percentages  is  multiplied 
by  the  bid  price  and  the  result  is  added  to  or  subtracted  from  the 
price  as  adjusted  for  B.t.u.  The  ash  adjustment  is  figured  to 
the  nearest  tenth  of  a  cent. 

As  an  example  of  the  method  of  determining  the  deduction  in 
cents  per  ton  of  coal  containing  ash  exceeding  the  standard  by 
more  than  2  per  cent,  suppose  coal  delivered  on  a  contract 
guaranteeing  10  per  cent  has  on  the  "dry-coal"  basis  shows  by 
analysis  to  have  14.50  per  cent,  the  deduction  according  to  this 
method  would  be  \  (4.50)  X  price  corrected  for  B.t.u.1 

The  Formulation  of  Proposals. — The  coal  operator  should  know 
what  guarantee  he  can  maintain  in  making  up  his  bid.  The 
purchaser  should  be  able  to  determine  the  likelihood  of  the  opera- 
tor being  able  to  fulfill  his  guarantee  without  excessive  penalties. 
Where  unit  coal  values  are  known  for  a  particular  mine  or  dis- 
trict this  information  is  a  simple  matter  of  calculation  and  has 
already  been  explained  on  page  60.  Table  VII  of  average  unit 
values  for  the  producing  counties  will  furnish  the  initial  data. 

1  Methods  of  sampling  and  specifications  for  the  government:  U.  S. 
Bureau  of  Mines,  Butt.  116,  p.  51,  1916. 


CHAPTER  X 
COMBUSTION  OF  COAL 

General  Principles. — The  difficulties  attending  the  complete 
combustion  of  bituminous  coal  are  directly  related  to  the  volatile 
matter  present.  The  showing  of  large  volumes  of  smoke,  there- 
fore, is  a  sure  sign  of  serious  loss  of  the  fuel  constituents.  The 
underlying  principles  furnish  a  sufficient  explanation  for  the 
losses  which  accompany  heavy  smoke.  A  brief  enumeration, 
therefore,  is  here  given: 

(a)  At  temperatures  below  400°C.  about  one-half  of  the  total 
volatile  matter  of  bituminous  coal  is  discharged. 

(6)  The  first  distillates  at  these  lower  temperatures  are  com- 
posed of  water  vapor,  oxides  of  carbon,  some  hydrogen  and 
methane,  but  chiefly  the  so-called  heavy  hydrocarbons,  ethylene, 
propylene,  benzene,  etc.,  including  also  some  compounds  which 
are  light  oils  and  tars  at  ordinary  temperature. 

(c)  Under  the  most  favorable  conditions  it  is  difficult  to  burn 
these  heavier  compounds  without  producing  a  smoky  flame,  a 
prerequisite  being  a  much  larger  mixture  of  air  than  that  required 
for  the  distillates  which  come  off  at  the  higher  temperatures, 
mainly  methane  (CEU)  and  hydrogen. 

(d)  A  high  percentage  of  moisture,  which  is  also  discharged 
simultaneously  with  the  heavy  hydrocarbons,  accentuates  the 
difficulty  by  sudden  expansion  into  steam  and  consequent  dis- 
placement of  air,  as  well  as  by  lowering  the  temperature  of 
the  combustion   chamber  while  the  process  of  vaporization  is 
proceeding. 

From  this  enumeration,  it  is  evident  that  to  discharge  these  first 
distillates  into  a  relatively  cooler  zone  emphasizes  the  unfavor- 
able conditions  for  combustion  and  results  also  in  a  condensation 
of  some  of  the  compounds,  all  of  which  is  made  evident  by  the 
appearance  of  dense  volumes  of  smoke.  This  is  always  the  result 
s  65 


66  FUEL,  GAS,  WATER  AND  LUBRICATION 

with  house-heating  appliances  and  is  more  or  less  evident  with 
all  steam-generating  devices  which  are  fired  intermittently. 

The  mechanical  or  physical  features  essential  to  smokeless 
combustion  are  now  well  understood  as  the  result  of  the  elaborate 
experiments  carried  on  by  various  investigators.1  The  two 
fundamental  elements  involved  are:  First,  a  continuous  acces- 
sion of  fuel  by  some  system  of  automatic  stoking;  and,  second, 
the  discharge  of  the  volatile  products  into  a  highly  heated  com- 
bustion zone  for  accomplishing  both  the  necessary  admixture  of 
air  and  the  completion  of  the  oxidation  processes  before  coming 
in  contact  with  the  relatively  cool  surfaces  of  the  boiler  tubes. 

Oxygen  Supply. — One  pound  of  pure  carbon  requires  theoreti- 
cally y|  or  2f  Ib.  of  oxygen  for  complete  combustion.  Since  23 
per  cent,  of  the  air  by  weight  is  oxygen,  1  Ib.  of  carbon  requires 
11.58  Ib.  of  air.  For  any  reasonable  degree  of  efficiency  under 
the  conditions  prevailing  in  the  average  combustion  device, 
this  amount  of  air  must  be  increased  by  at  least  50  per  cent. 
Very  much  depends,  however,  upon  the  distribution  of  air  allow- 
ance. The  volatile  hydrocarbons  which  are  discharged  from 
the  fuel  bed  are  at  a  double  disadvantage.  Not  only  are  they 
particular  in  the  matter  of  temperature  at  which  they  will 
maintain  combustion  and  the  ready  accessibility  of  their  oxygen 
supply,  but  they  are  further  handicapped  by  the  fact  that  this 
oxygen  supply  is  haphazard  in  amount  and  not  easily  adjusted 
to  meet  the  varying  requirements  of  the  volatile  matter.  This  is 
the  more  readily  appreciated  when  it  is  remembered  that  any 
combustion  processes  taking  place  in  the  combustion  chamber 
above  the  fuel  bed  must  come  from  openings  above  the  grates, 
since  practically  no  air  with  free  or  unused  oxygen  can  come 
through  the  fuel  bed.2  This  involves  numerous  considerations, 
perhaps  more  mechanical  than  chemical,  such  as  distribution  of 
openings,  size  of  combustion  space,  completeness  of  mixing  and 
pressure  of  gases  within  the  furnace  or  "  drafts."  These  consider- 
ations have  a  vital  bearing,  especially  upon  a  number  of  topics 
relating  to  good  efficiencies  in  combustion,  only  a  few  of  which 
can  be  referred  to  here. 

1  BEMENT,    A.,    Jour.    Western    Soc.    Eng.,    vol.  13,     2,   pp.    209-282, 
April,  1908. 

2  U.  S.  Bureau  of  Mines,  Butt.  136,  1917. 


COMBUSTION  OF  COAL 


67 


Smoke. — It  is  evident  from  the  preceding  discussion  that 
smoke  reduction  depends  upon  (a)  admission  of  air  above  the 
fuel  bed,  (6)  thorough  mixing,  and  (c)  the  maintenance  of  a  tem- 
perature above  the  ignition  point  of  the  gases  and  vapors  involved. 
Failure  on  the  part  of  any  one  of  these  three  conditions  will 
result  in  smoke  where  bituminous  coal  is  being  burned.  In 
house-heating  appliances  only  the  first  condition,  (a),  can  be 
employed  to  any  practical  degree  and  this  especially  under  the 
conditions  of  intermittent  firing  is  for  all  practical  purposes, 
substantially  lacking.  Hence,  as  a  general  statement,  it  may  be 
said  that  all  house-heating  appliances  produce  smoke.  In  the 


FIG.   16. — Stoker  boiler,  showing  tile  baffling. 

aggregate  this  is  more  than  that  produced  by  factories  and  small 
establishments  combined. 

In  the  case  of  large  installations  the  conditions  under  (a)  and 
(6)  are  the  most  readily  provided  through  the  use  of  stokers 
which  avoid  the  intermittent  conditions  which  accompany  hand 
firing.  A  steady  accession  of  fuel  results  in  a  uniform  discharge 
of  volatile  combustible,  which  can  be  met  with  reasonable  accu- 
racy by  a  definite  admission  of  air  above  the  fuel.  Varying  loads 
and  varying  draft  pressures  however  complicate  the  problem. 

The  most  difficult  condition  of  all  to  meet  is  that  under  (c)  or 
(6)  and  (c)  combined.  The  ignition  temperature  of  the  more 
common  gases  discharged  into  the  combustion  chamber  such  as 


68 


FUEL,  GAS,  WATER  AND  LUBRICATION 


methane,,  for  example,  is  from  650  to  750°C.  or  a  mean  of  700°C. 
(1,300°F.)  and  for  hydrogen  it  has  an  average  ignition  tempera- 
ture of  585°C.  or  l^SST.1 
The  temperature  of  the  flues  in  a  water  tube  boiler  doubtless 


FIG.   17. — Sectional  view  of  stoker  and  boiler. 

never  exceeds  200°C.,  (425°F.)  at  300-lb.  gage  pressure.2  Among 
the  more  common  methods  for  securing  the  necessary  tempera- 
tures are  those  which  provide  a  longer  combustion  chamber. 
This  may  be  secured  horizontally,  as  in  the  tile  baffling  of  the 

1  DIXON  and  COWARD,  Jour.  Chem.  Soc.,  vol.  95,  p.  519,  1909. 

2  See  MARKS  and  DAVIS,  "Steam  Tables,"  Longmans,  Green  Co. 


COMBUSTION  OF  COAL 


69 


lower  flues,  Fig.  16,  or  by  elevating  the  boiler  above  the  fuel  bed  as 
shown  in  Fig.  17,  where  the  extreme  height  between  the  fire  and 
flues  may  average  as  much  as  15  ft.  A  good  illustration  is 
shown  in  Fig.  18  of  the  effect  of  cooling  the  gases  discharged  from 
the  fuel  bed  below  the  temperature  of  ignition  before  combustion 
is  complete. 


FIG.    18. — Stoker  and  boiler,  showing  effect  of  cooling  the  gases  below  their 
ignition  temperatures. 

Clinker  Formation. — The  worst  enemy  of  efficiency  in  the 
burning  of  bituminous  coal  is  any  condition  of  fusion  or  cementa- 
tion of  the  constituents  of  the  fuel  bed  in  such  a  manner  as  to 
impede  or  block  off  the  passage  of  air  and  products  of  combustion 
through  the  mass.  The  organic  matter  of  some  coals  has  a 
tendency  to  fuse  readily  or  "cake,"  but  this  property,  to  the 
extent  of  interfering  with  the  free  burning  of  coals  of  the 
Illinois  type,  is  not  of  a  serious  nature.  A  much  more  difficult 
problem  resides  in  the  tendency  of  these  coals  to  clinker. 
Clinker,  in  the  ordinary  sense,  is  the  fusion  of  the  inorganic  or 
ash  constituents  of  the  coal  into  masses  that  interfere  with  the 
free  access  of  air.  Under  normal  conditions,  from  10  to  25  per 
cent  of  the  total  combustible  is  discharged  into  the  combustion 
chamber  for  burning  above  the  fuel  bed.  The  formation  of 
clinker  tends  to  greatly  increase  this  ratio.  The  shortage  of 
oxygen  also  promotes  the  formation  of  carbon  monoxide  and 


70  FUEL,  GAS.  WATER  AND  LUBRICATION 

increases  the  amount  of  unburned  material  passing  out  with  the 
ash.  Moreover,  the  formation  of  clinker  tends  to  produce  more 
clinker,  for  reasons  that  will  readily  appear.  Coals  with  a  high 
percentage  of  pyritic  iron  FeS2  have  a  readily  melting  constituent 
in  that  material.  The  melting  point  of  FeS2  is  only  1,171°C.,  and 
even  though  it  decomposes  with  heat,  the  resulting  compound, 
FeS  melts  at  about  the  same  temperature  1,197°C.  The  latter 
compound  is  quite  stable  so  far  as  dissociation  is  concerned,  and 
if  nothing  occurs  to  change  its  composition,  it  may,  if  present  in 
considerable  quantity,  flow  down  upon  or  through  the  grates, 
having  a  consistency  something  like  molasses.  If  the  grates 
become  covered  with  such  material,  the  cooling  effect  of  the  air 
is  lost  and  the  grates  quickly  burn  out. 

If,  on  the  other  hand,  the  conditions  of  combustion  are  kept 
active  so  that  all  of  the  sulphur  is  burnt  and  the  iron  oxidized  to 
Fe203,  the  fusing  point  of  the  latter  is  1,548°C.  and  that  condition 
of  complete  oxidation,  if  accomplished,  practically  eliminates 
the  possibility  of  clinker  formation.  The  accomplishing  of  this 
state  of  complete  oxidation  involves  perhaps  more  physical 
conditions  than  otherwise.  Lump  coal  or  sized  egg  or  nut  will 
retain  open  passage-ways  and  thus  promote  oxidation.  Slack 
or  screenings  or  mixed  smaller  sizes  will  impede  the  free  access 
of  air.  Such  coals  in  house  heaters  will  be  very  prolific  of  clinkers, 
Most  mechanical  stokers,  especially  of  the  under-feed  type,  tend 
to  keep  the  fuel  mass  broken  up  so  that  the  air  has  access.  In 
locomotives  and  fuel  beds  of  unusual  width  or  depth  where  exces- 
sive draft  is  essential,  the  carrying  of  smaller  particles  of  the  low 
fusing  constituents  by  means  of  the  strong  draft  currents  results 
in  "  honey-combing "  of  flue  sheets  or  the  spaces  between  water 
tubes  to  such  an  extent  that  the  passage-ways  are  seriously 
reduced  or  cut  off  altogether.  The  most  obvious  remedy  is  to 
increase  the  air  supply  to  the  fuel  bed  or  maintain  conditions 
which  will  result  in  more  positive  oxidizing  conditions  whereby 
the  resulting  ash  shall  not  have  an  admixture  of  iron  in  the  form 
of  FeS.1 

Fusibility  of  Ash. — Much  importance  is  being  placed  at  the 
present  time  on  the  fusibility  of  ash  and  specifications  covering 

1  PARR,  S.  W.,  Honeycomb  and  clinker  formation  in  locomotives:  Proc. 
International  Ry.  Fuel  Assn.,  1914. 


COMBUSTION  OF  COAL  71 

the  methods  for  that  determination  have  been  adopted.1  There 
may  be  very  little  relation  between  the  fusibility  of  the  ash  as 
made  ready  for  such  a  test  and  the  same  ash  under  adverse 
conditions  of  combustion  where  insufficient  air  and  a  strongly 
reducing  environment  is  maintained  with  a  coal  of  high  pyritic 
content. 

The  Wetting  of  Coal. — From  the  previous  discussion  as  to  the 
cause  of  clinker  formation  a  sufficient  reason  is  afforded  for  the 
practice  of  wetting  down  the  coals  before  firing  the  same  under 
the  boiler.  The  larger  use  of  screenings  with  the  mechanical 
stokers  now  in  vogue  and  the  higher  percentage  of  iron  pyrites 
in  such  fuel  of  the  smaller  sizes2  makes  a  brief  reference  to  this 
practice  of  coal  wetting  desirable. 

The  FeS2  of  coal  when  it  reaches  the  combustion  zone  of  the 
fuel  bed  readily  changes  to  FeS.  In  this  condition  it  may  be 
decomposed  by  steam.  Some  of  the  reactions  involved  are 
shown  by  the  equation : 

2FeS  +  7H20  +±  Fe2O3  +  2S02  +  7H2 

Verification  of  some  of  these  conditions  is  afforded  when  a 
stream  of  water  is  turned  on  a  red  hot  clinker,  the  odor  of  S02 
being  very  marked.  Similarly,  without  being  able  to  assign  any 
reason  for  it,  a  fireman  will  maintain  that  a  pool  of  water  retained 
under  the  grates  and  from  which  the  steam  rises  into  the  fuel 
bed  will  promote  a  better  combustion  of  the  coal.  The  natural 
argument  would  seem  to  be  against  the  wetting  of  coal.  The 
latent  heat  of  vaporization  of  the  added  water  is  lost,  and  the 
dissociation  of  the  water  into  hydrogen  and  oxygen  requires  as 
much  heat  as  is  produced  by  their  recombination  in  the  com- 
bustion chamber.  However,  the  practical  result  of  an  open  fire 
bed  and  a  reduction  of  the  clinkering  effect  decidedly  outweighs 
the  theoretical  considerations  against  the  wetting  down  of  the 
coal. 

Another  consideration  from  the  chemical  standpoint  would  be 

1  FIELDNER,  A.  C.,  Tentative  method  for  determining  the  fusibility   of 
ash:  Am.  Soc.  for  Testing  Mat.,  1920. 

2  POWELL  and  PARR,  Forms  of  sulphur  in  coal :  Univ.  of  111.  Eng.  Exp. 
Sta.,  Bull.  111. 

YANCEY  and  FRASER,  Distribution  of  the  forms  of  sulphur  in  the  coal 
bed:  Jour.  Ind.  and  Eng.  Chem.,  pp.  13-35,  1921. 


72  FUEL,  GAS,  WATER  AND  LUBRICATION 

as  follows:  Water  vapor  passing  through  or  coming  in  contact 
with  an  incandescent  fuelled  would  form  water  gas  to  a  very 
considerable  extent.  The  gases,  H2  and  CO,  upon  recombining 
would  regenerate  only  the  heat  lost  in  their  formation,  but  their 
ignition  temperatures  would  permit  of  a  continuation  of  the 
combustion  process  within  the  relatively  cooler  zones  of  the 
system,  as  for  example  in  the  flue  spaces.  The  heat  thus  devel- 
oped would  promote  the  further  burning  of  those  hydrocarbons 
which  require  a  high  temperature  for  their  complete  combustion, 
such  as  marsh  gas,  etc.  Under  certain  circumstances,  therefore, 
where  the  conditions  approximate  those  above  outlined,  it  is 
entirely  possible  that  the  wetting  of  coal  may  result  in  an  actual 
increase  of  efficiency. 

Other  considerations  might  be  referred  to  of  a  more  physical 
type.  In  the  case  of  finely  divided  material  the  water  bonding 
effect  may  tend  to  hold  the  particles  in  place  until  the  heat 
reaches  the  coking  or  caking  stage  with  the  result  that  less  solid 
fuel  is  drawn  through  the  combustion  chamber  into  the  stack 
without  burning. 

Whether  these  explanations  adequately  cover  the  case  or  not, 
the  fact  remains  that  with  the  finer  sizes  of  Illinois  coals  the 
every-day  experience  in  the  boiler  room  is  decidedly  in  favor  of 
the  wetting-down  process. 


CHAPTER  XI 
STORAGE,  WEATHERING,  AND  SPONTANEOUS  COMBUSTION 

Deterioration. — Coal  is  subject  to  deterioration  from  the  time 
of  breaking  out  at  the  mine  until  used.  These  losses,  however, 
are  relatively  small.  A  sudden  drop  occurs  in  the  first  week  or 
two,  due  no  doubt  to  the  liberation  of  certain  of  the  hydro- 
carbons. Subsequent  losses  are  more  largely  due  to  the  adsorp- 
tion of  oxygen  and  the  formation  of  humic  compounds  which  are 
part  of  the  subsequent  coal  texture.  The  cut  herewith  shown, 
Fig.  19,  is  typical  and  illustrates  the  kind  and  amount  of  losses 
over  the  space  of  one  year's  storage.1 

Perhaps  even  more  serious  than  the  loss  by  weathering  is  the 
disintegration  or  slaking  which  takes  place,  whereby  the  coal  is 
reduced  in  size.  It  is  thus  rendered  more  difficult  to  maintain  a 
proper  circulation  of  air  through  the  fuel  bed.  The  matter  of 
weathering  is  discussed  in  detail  in  Bulletin  38  of  the  Illinois 
Engineering  Experiment  Station. 

Spontaneous  Combustion. — All  coals  of  the  bituminous  type 
are  subject  to  spontaneous  combustion.  A  detailed  study  of 
the  causes  has  been  made  in  Bulletin  46  of  the  Illinois  Engi- 
neering Experiment  Station.2  Briefly  summarized,  they  are  as 
follows : 

1.  The  oxidation  of  coal  is  continuous  over  a  wide  range  of 
time  and  conditions,  and  begins  with  the  freshly  mined  coal  at 
ordinary  temperatures.  A  number  of  oxidation  processes  are 
involved  which  are  more  or  less  distinct  in  character,  some  being 
relatively  slow  and  moderate  in  form,  while  others  are  rapid  and 
vigorous  in  their  action. 

1  PARR  and  WHEELER,  The  weathering  of  coal:  Univ.  of  111.  Eng.  Exp. 
Sta.,  Bull.  38. 

PARR,  S.  W.,  Effect  of  storage  upon  the  properties  of  coal:  Univ.  of  111. 
Eng.  Exp.  Sta.,  Bull  97. 

2  PARR,  S.  W.  and  KRESSMANN,  F.  W.,  The  spontaneous  combustion  of 
coal:  Univ.  of  111.  Eng.  Exp.  Sta.,  Bull  46. 

73 


74 


FUEL,  GAS,  WATER  AND  LUBRICATION 


2.  In  general,  we  may  say  that  for  a  given  coal  a  point  exists 
as  indicated  by  the  temperature,  below  which  oxidation  is  not 
ultimately  destructive  and  its  continuance  is  dependent  upon 
certain  accessory  conditions  which,  if  withdrawn,  the  oxidation 


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EXPOSED  BINS 
COVERED  BINS 
UNDER  WATER 

— 

— 

FIG.  19. — Vermilion  County,  Illinois,  screenings  showing  the  loss  in  heat 
value  for  the  first  two  weeks,  and  for  each  month  following  throughout  the 
year. 


ceases.  On  the  other  hand,  above  this  critical  point,  which  is 
best  indicated  by  temperatures,  oxidation  is  ultimately  destruc- 
tive and  is  characterized  by  the  fact  that  it  does  not  depend 
for  its  continuance  upon  external  conditions,  but  is  self-propelling 
or  autogenous. 


STORAGE  AND  SPONTANEOUS  COMBUSTION  75 

3.  The  point  of  autogenous  oxidation,  while  varying  for  differ- 
ent conditions,  may  be  indicated  by  temperatures  of  the  mass 
ranging  from  200  to  275°C.,  depending  to  a  great  extent  upon  the 
fineness  of  division.     The  phenomenon  of  fire  or  actual  kindling 
does  not  occur  until  a  much  higher  temperature  is  reached, 
usually  beyond  350°C. 

4.  The  temperature  at  which  autogenous  oxidation  begins  is 
the  sum  of  numerous  temperature  components,  each  one  of  which, 
either  because  of  its  own  contribution  to  the  total  heat  quantity 
or  because  of  its  function  as  a  booster  for  chemical  activities, 
must  be  looked  upon  as  a  dangerous  factor  tending  directly  to 
the  ultimate  result  of  active  combustion  throughout  the  mass. 
An  enumeration  of  the  more  important  elements  which  contribute 
towards  this  end  are  the  following: 

(a)  External  Sources  of  Heat. — Oxidation,  especially  of  the 
lower  or  moderate  form,  is  greatly  accelerated  and  in  certain 
phases  directly  dependent  upon  an  increase  of  temperature. 
What  may  be  termed  external  or  physical  sources  of  heat, 
and  thus  presumably  avoidable,  are  suggested  by  the  following: 

1.  Contact  of  the  mass  with  steam  pipes,  hot  walls  or  floors 
under  which  are  placed  heat  conduits  of  any  sort. 

2.  The  heat  of  impact  or  pressure  due  to  the  method  of  unload- 
ing or  to  the  depth  of  piling. 

3.  Climatic  or  seasonal  temperature  at  the  time  of  storage. 

4.  The  direct  absorption  of  heat  from  the  sun  or  from  reflecting 
surfaces. 

(6)  Fineness  of  Division. — Coal  in  a  fine  state  of  division 
presents  a  very  much  larger  surface  and  brings  a  much  larger 
quantity  of  reacting  substances  in  contact  with  oxygen  than  when 
in  solid  masses.  Under  these  conditions,  with  a  condensation 
or  accumulation  of  relatively  large  amounts  of  oxygen  immedi- 
ately surrounding  or  in  contact  with  the  particles  of  carbonaceous 
matter,  the  circumstances  are  exceedingly  favorable  for  rapid 
oxidation  upon  the  arrival  of  the  mass  to  a  suitable  temperature. 
But,  more  especially  does  this  fineness  of  division  facilitate  the 
initial  form  of  oxidation  described  under  (c)  below. 

(c)  Easily  Oxidizable  Compounds. — An  initial  stage  of  oxi- 
dation exists  in  bituminous  coals  which  does  not  result  in  the  for- 
mation of  carbon  oxide.  There  are  present  in  coals  of  this  type 


76  FUEL,  GAS,  WATER  AND  LUBRICATION 

unsaturated  compounds  which  have  a  marked  avidity  for  oxygen 
at  ordinary  temperatures,  the  products  being  humic  acid  or 
other  fixed  constituents  of  the  coal  texture.  Coals  vary  widely 
in  this  matter  and  it  has  been  proposed  by  some  to  regard  this 
property  as  an  index  of  the  liability  to  spontaneous  combustion. 
It  is,  however,  very  largely  dependent  upon  the  freshness  of  the 
coal  and  upon  the  fineness  of  division  (see,  under  (6)  above). 
The  colloidal  character  of  coal  gives  it  peculiar  properties  as  an 
adsorptive  medium,  especially  for  oxygen.  The  adsorptive 
process  itself  generates  a  small  increment  of  heat  and  the  greater 
the  adsorption,  as  in  case  of  fine  coal,  the  greater  the  amount  of 
such  heat.  Moreover  the  adsorption  of  oxygen  is  greatly  acceler- 
ated as  the  temperature  rises,  so  that  the  difficulty  is  cumulative. 
One  peculiarity  of  the  process  is  that  the  oxygen  thus  adsorbed 
is  so  tenaciously  held  by  the  coal  that  with  the  rise  in  temperature 
it  is  not  discharged  as  oxygen,  but  in  the  main  is  retained  until 
actual  chemical  union  is  brought  about  resulting  in  the  formation 
of  H20  and  CC>2  with  the  natural  accompaniment  of  heat  (see 
also  discussion  under  (/)). 

(d)  Iron  Pyrites. — The  presence  of  sulphur  in  the  form  of  iron 
pyrites  is  a  positive  source  of  heat  due  to  the  reaction  between 
sulphur  and  oxygen.  Here  again  rapidity  of  oxidation  is  directly 
dependent  upon  fineness  of  division.  Since  coals  of  the  Mid- 
Continental  field  especially  have  a  much  higher  earthy  or  ash 
content  in  the  fine  material,  and  since  iron  pyrites  is  a  large 
component  of  this  substance,  it  follows  that  the  presence  of  dust 
or  duff  in  all  coals  of  the  Illinois  type  is  a  positive  source  of 
danger.  Since  coals  of  the  Illinois  or  Mid-Continental  field 
have  in  the  larger  number  of  cases  iron  pyrites  averaging  over  5 
per  cent  or  as  sulphur  above  2.5  per  cent,  the  heat  increment  from 
the  oxidation  of  only  one-fifth  of  this  material  is  sufficient  to  raise 
the  temperature  of  the  mass  approximately  70°,  assuming  that 
there  is  no  loss  by  radiation.  Under  usual  conditions,  and 
especially  considering  the  greatly  accelerated  rate  of  chemical 
activity  accompanying  a  rise  of  temperature,  this  oxidation  may 
proceed  with  such  rapidity  that  the  heating  up  of  the  mass  will 
be  but  little  affected  by  the  loss  of  heat  due  to  radiation,  except 
in  relatively  shallow  piles.  Coals  of  low  sulphur  content  or  such 
as  do  not  have  sulphur  greatly  in  excess  of,  say  1.5  per  cent  are 


STORAGE  AND  SPONTANEOUS  COMBUSTION  77 

popularly  supposed  to  be  immune  from  heating,  but  no  method  of 
selection  or  hand-picking  at  the  mine  can  eliminate  all  of  the 
iron  pyrites.  Lumps  of  coal,  to  all  outward  appearance  of  good 
texture,  may  have  nodules  or  detached  bands  of  iron  pyrites. 
These  become  centers  of  activity  and  with  the  addition  of  moisture 
such  coal  will  have  many  scattered  spots  where  heating  begins. 
If  fine  coal  is  mixed  in  with  the  coarse,  the  difficulty  is  accentu- 
ated. Doubtless  a  complete  separation  of  fine  and  lump  material 
in  such  cases  would  lessen  the  danger. 

(e)  Moisture. — Moisture,  while  essential  to  pyritic  oxidation, 
is  given  separate  mention  because  its  importance  is  apt  to  be 
underestimated.  Any  coal  with  pyritic  conditions  as  •  above 
mentioned  will  be  facilitated  in  that  action  by  moisture.  It  is 
to  be  noted  in  this  connection  that  the  normal  water  content  or 
vein  moisture  of  coals  in  this  central  region  is  rarely  below 
10  per  cent  and  ranges  usually  from  12  per  cent  to  15  per  cent. 
The  presence  of  such  water  must  be  borne  in  mind  in  considering 
the  likelihood  of  chemical  activity  on  the  part  of  the  pyrites 
present. 

(/)  The  Oxidation  of  Carbon  and  Hydrogen. — A  third  stage  of 
oxidation  of  the  carbonaceous  material  exists  by  reason  of  the 
property  of  certain  of  the  hydrocarbon  compounds  of  coal  to 
oxidize  with  the  formation  of  CO2  and  H^O  at  temperatures  in 
excess  of  120  to  140°C.  Though  this  type  of  oxidation  does  not 
take  place  appreciably  at  ordinary  temperatures,  it  must  be 
looked  upon  as  an  exceedingly  dangerous  stage  in  the  process 
of  oxidation,  owing  to  the  very  much  higher  quantity  of  heat 
which  is  discharged  by  the  oxidation  of  carbon  and  hydrogen;  so 
that  the  temperature  of  autogenous  action,  though  ordinarily 
occurring  at  a  higher  point  by  100°  or  more,  may  be  quickly 
attained  as  a  result  of  this  form  of  oxidation.  Any  initial  heat 
increments,  therefore,  which  threaten  to  bring  the  chemical 
activities  along  to  the  point  where  the  oxidation  processes  invade 
the  carbonaceous  material  in  this  manner  must  be  looked  upon 
as  dangerous.  For  example,  any  of  the  initial  or  contributory 
processes  which  result  in  raising  the  temperature  of  the  mass  50° 
above  the  ordinary  temperature  would,  in  all  probability,  have 
enough  material  of  the  sort  involved  in  such  action  to  continue 
the  activity  until  another  50°  had  been  added,  which  would 


78  FUEL,  GAS,  WATER  AND  LUBRICATION 

thereby  attain  to  the  condition  wherein  this  third  stage  of  oxida- 
tion would  begin. 

(g)  Autogenous  Oxidation. — The  fourth  stage  of  oxidation  may 
be  indicated  as  occurring  at  temperatures  above  200  to  275°C.  and 
differs  from  the  previous  stages  in  that  the  action  is  autogenous 
and  not  dependent  upon  other  sources  of  heat  to  keep  up  the 
reacting  temperature.  Activity  in  this  stage  is  further  acceler- 
ated by  the  fact  that  above  300°  the  decomposition  of  the  coal 
begins  which  is  exothermic  in  character,  thereby  contributing 
somewhat  to  a  further  increase  in  temperature.  The  ignition 
temperature  is  reached  at  a  point  still  further  along,  usually  in 
excess  of  300  to  400°C. 

Storage  Methods. — The  above  formulation  of  various 
stages  and  types  of  oxidation  clearly  indicates  the  principles 
which  must  be  observed  in  any  attempt  at  the  prevention  of 
spontaneous  combustion.  The  following  enumeration,  there- 
fore, of  preventive  or  precautionary  measures  is  to  be  considered 
as  suggestive  rather  than  complete  in  character: 

First. — The  avoidance  of  external  sources  of  heat  which  may  in 
any  way  contribute  toward  increasing  the  temperature  of  the 
mass  is  a  first  and  prime  essential. 

Second. — There  must  be  an  elimination  of  coal  dust  or  finely 
divided  material.  This  will  reduce  to  a  minimum  the  initial 
oxidation  processes  of  both  the  carbonaceous  matter  and  the 
iron  pyrites.  These  lower  forms  of  oxidation  are  to  be  looked 
upon  as  boosters,  without  which  it  would  be  impossible  for  the 
more  lively  and  destructive  activities  to  become  operative. 

Third. — Dryness  in  storage  and  a  continuation  of  the  dry 
state,  together  with  an  absence  of  finely  divided  material,  would 
practically  eliminate  the  oxidation  of  the  iron  pyrites.  The 
drenching  down  with  water  of  heating  piles,  where  the  sulphur 
content  is  high  and'uniformly  distributed,  accentuates  the  diffi- 
culty. Where  pyritic  activity  is  localized  in  spots  or  is  so  small 
in  amount  as  to  reach  a  possible  exhaustion,  the  drenching  with 
water  may  check  the  heating  or  prolong  the  action  so  that  oxi- 
dation of  the  carbonaceous  matter  does  not  get  under  way  to  a 
serious  extent.  In  such  cases,  however,  there  is  no  ultimate 
safety  except  in  the  removal  of  the  heated  zones. 

Fourth. — The  submerging  of  coal,  it  is  very  evident,  will  elimi- 


STORAGE  AND  SPONTANEOUS  COMBUSTION  79 

nate  all  of  the  elements  which  contribute  towards  the  initial 
temperatures.  As  to  its  industrial  practicability  it  can  best  be 
determined  by  actual  experience. 

Fifth.- — The  storing  of  coal  should  be  made  in  sized  lumps  only. 
The  air  spaces  are  greater  of  course  in  any  given  size  than  in  a 
mixture  of  sizes.  Such  massses  provide  a  relatively  free  circu- 
lation of  air  whereby  the  small  initial  increments  of  heat  are 
carried  off.  However,  if  spots  occur  in  the  mass  where  fine 
material  has  been  dumped  or  formed,  this  same  free  circulation 
of  air  makes  such  spots  especially  dangerous. 

Sixth. — Coal  may  be  stored  in  the  finely  divided  condition, 
provided  it  is  all  fine  material  with  no  lumps  to  open  up  air 
passages,  and  provided  further  that  the  material  as  stored  is 
packed  uniformly  so  as  to  exclude  the  admission  of  air. 

It  is  as  dangerous  to  store  fine  coal  with  accessory  conditions 
admitting  free  access  of  air,  such  as  lumps  or  passage-ways  held 
open  by  posts,  supports  or  structural  features  of  retaining  walls, 
as  it  is  to  store  lump  coal  with  occasional  zones  where  fine  material 
is  allowed  to  form  or  where  an  occasional  load  of  mixed  fine  and 
coarse  stuff  is  dropped,  or  where  coarse  material,  properly  sized, 
is  stored  against  or  in  contact  with  fine  material  in  storage. 
The  line  of  contact  will  be  a  certain  source  of  fire.1 

1  See  the  Storage  of  bituminous  coal,  by  H.  H.  STOEK,  Univ.  of  111.  Eng. 
Exp.  Sta.,  Circular  6,  1918.  Also,  the  Effect  of  storage  upon  the  properties 
of  coal,  by  S.  W.  PARR,  Univ.  of  111.  Eng.  Exp.  Sta.,  Bull  97. 


CHAPTER  XII 
COKE 

General  Statement. — Under  the  second  division  of  solid 
fuels  is  included  coke  and  other  forms  of  artificially  prepared 
material,  such  as  charcoal,  briquettes,  etc.  Coke  occupies  by 
far  the  largest  place  in  the  list  of  manufactured  fuels.  The 
yearly  production  approximates  52,000,000  tons.  Of  this  a 
small  portion  is  used  in  domestic  appliances.  For  such  purposes 
the  low  content  of  volatile  matter,  not  over  2  per  cent,  requires 
some  care  in  the  matter  of  draft  regulation,  low  fires  are  not  as 
easily  managed  as  where  more  active  conditions  are  maintained. 
As  one  element  in  the  attempt  to  overcome  this  difficulty  "low 
temperature"  carbonization  is  now  receiving  much  attention. 
The  coke  product  of  such  treatment  should  have  an  average  of 
10  or  12  per  cent  volatile,  though  this  constituent  can  probably 
be  varied  between  5  and  15  per  cent.  This  would  greatly 
simplify  the  matter  of  combustion  control  in  household  use. 

It  is  not  intended  here  to  go  into  a  detailed  discussion  of  the 
low-temperature  process.  The  topic  should  not  be  passed, 
however,  without  brief  reference.  If  ever  such  a  process  becomes 
practicable,  it  will  doubtless  profoundly  affect  the  entire  coke, 
gas,  and  tar  industries.  At  the  present  time  no  such  process  has 
been  developed  to  the  point  of  a  commercial  success  in  this 
country.  The  experimental  work  being  carried  on  for  many 
years  at  the  University  of  Illinois  has  had  as  a  fundamental 
object  the  development  of  a  theory  of  carbonization  applicable 
to  high-oxygen  coals  of  the  Illinois  type.  The  present  status 
of  this  and  some  of  the  more  advanced  developments  are  best 
referred  to  in  current  technical  literature.1 

Metallurgical  Coke. — By  far  the  chief  use  of  coke  is  in  the 
blast  furnace  for  the  reduction  of  iron*ore.     Fromf  1,600  to  1,800 
Ib.  or  slightly  less  than  1  ton  of  coke  is  required  for  the  production 
1  Symposium  on  fuels,  Jour.  Ind.  and  Eng.  Chem.,  January,  1921. 

80 


COKE  81 

of  1  ton  of  pig  iron.  Approximately  40,000,000  tons  of  coke  are 
used  annually  in  the  United  States  in  the  manufacture  of  pig  iron. 
Incidentally,  it  should  be  noted  that  after  doing  the  work  of 
reduction  on  the  iron  ore,  the  discharged  gases  have  a  positive 
value  as  a  fuel,  hence  the  blast  furnace  may  be  looked  upon  as  an 
appliance  for  the  manufacture  of  producer  gas  on  an  enormous 
scale.  Approximately  5  tons  of  gas  pass  out  of  the  blast  furnace 
for  each  ton  of  pig  iron  produced,  and  from  25  to  30  per  cent 
of  this  is  carbon  monoxide.  It  has  been  estimated1  that  a  net 
potential  value  of  approximately  850  hp.  might  be  available  for 
every  ton  of  iron  produced  per  hour.  At  the  moderate  estimate 
of  2,000  tons  of  iron  per  hour  in  this  country  there  would  be 
represented  over  1,500,000  hp.  available  per  hour  as  a  by-product 
of  the  blast  furnaces  alone.  The  largest  power  plant  in  the 
world  operating  on  blast-furnace  gas  led  directly  after  scrubbing 
to  high-compression  engines,  is  located  at  Gary,  Ind.,  where  the 
gas  from  eight  blast  furnaces  supplies  39  gas  engines  developing 
142,875  hp.  per  hour.  In  1913  the  total  installations  of  blast 
furnaces  in  the  United  States  represented  a  potential  generation 
of  339,280  hp.  per  hour,  or  over  11,000,000,000  hp.  per  year. 

Sampling  and  Analysis. — Methods  for  the  sampling  and 
analysis  of  coke  are  substantially  the  same  as  for  coal.  See 
the  reports  of  the  special  committee  of  the  American  Society 
for  Testing  Materials.2  One  or  two  peculiarities  of  the  mate- 
rial should  be  especially  noted  by  the  chemist. 

Pulverizing  of  Coke. — In  the  preparation  of  coke  for  analysis 
fine  grinding  is  not  so  easily  accomplished  as  in  the  case  of  raw 
coal.  Grinding  apparatus  using  iron  surfaces  may  give  up  ap- 
preciable amounts  of  metallic  iron  to  the  sample.  The  final 
reduction  is  best  made  in  an  agate  mortar. 

Volatile  Matter. — When  coke,  especially  in  the  finely  divided 
state,  is  cooled  down  from  a  red  heat,  it  has  marked  absorption 
properties,  especially  for  oxygen.  Upon  re-heating,  this  oxygen 
combines  with  the  carbon  or  absorbed  hydrogen  to  an  appreciable 
extent  and  is  given  off  as  H20  and  CO2,  thus  augmenting  the 
apparent  amount  of  volatile  matter.  For  this  reason  repeated 

ISTILLMAN'S  "Chemical  Engineering,"  4th  ed.,  p.  267. 
2  Committee  Reports,  Tentative  Standards:  Proc.,  19th  Annual  Meeting, 
Am.  Soc.  for  Testing  Mat.,  part  I,  p.  551,  1916. 


82  FUEL,  GAS,  WATER  AND  LUBRICATION 

volatile  matter  determinations  on  the  same  sample  seem  to  give 
an  indefinite  amount  of  volatile  matter. 

Sulphur. — Sulphur  in  coke,  like  oxygen  and  hydrogen  and 
doubtless  also  nitrogen,  is  held  in  a  surface  condensation  con- 
dition, and  not  as  a  sulphide  of  carbon,  in  the  ordinary  sense. 
The  original  organic  sulphur  compounds  have  been  decomposed, 
also  the  inorganic  sulphur  in  the  form  of  iron  pyrites  has  dis- 
charged practically  all  of  its  sulphur.  A  small  amount  only  may 
remain  as  pyrrhotite  or  magnetic  sulphide  of  iron.  The  sulphur 
thus  discharged,  mainly  in  the  form  of  H2S  readily  undergoes 
surface  absorption  or  adsorption  by  the  coke  at  low-red  heat,  and 
in  this  form  is  stable  even  at  1,000°C.  From  this  form,  however 
it  is  easily  discharged  under  oxidizing  and  alkaline  conditions 
either  by  fusion  in  sodium  peroxide  or  by  the  usual  Eschka 
method,  for  determination  as  SO3. 


CHAPTER  XIII 
WOOD 

Introduction. — Under  certain  conditions  and  in  certain  regions 
wood  and  wood  waste  have  a  fuel  value  which  may  attain  to 
technical  importance.  One  or  two  points  of  interest  should  be 
discussed  in  this  connection. 

No  attempt  has  been  made  to  apply  the  same  descriptive 
terms  to  wood  as  are  applied  to  coal.  For  example,  "dry" 
wood  has  no  specific  meaning,  such  as  "moisture-free"  or 
"oven-dry"  material.  It  probably  would  be  understood  to 
mean  simply  well  seasoned  wood  as  opposed  io  that  which  was 
green  or  unseasoned. 

Heat  Values. — Another  uncertainty  concerns  the  heat  value 
which  should  be  assigned  to  wood.  The  values  found  in  technical 
literature  are  either  totally  misleading  or  of  uncertain  value. 
The  earliest  values  were  derived  by  Berthier1  and  were  based  on 
the  so-called  Welter  law  which  held  that  the  union  of  one  and 
the  same  quantity  of  oxygen  with  any  of  the  elements  gave  the 
same  amount  of  heat.2 

Winkler  followed  the  same  method,  but  made  some  reference 
to  the  moisture  content  of  the  material,  which  was  supposed  to  be 
about  9  per  cent.  The  values  obtained  by  both  of  these  investi- 
gators are  occasionally  repeated  in  the  literature.3  They  are 
entirely  at  fault,  and  should  be  credited  with  only  historical  value. 

Rumford  in  1813  was  the  first  to  transmit  the  heat  of  wood  as 
it  burned  to  a  measured  quantity  of  water.  The  wood  was  dried 
in  a  chafing  dish  and,  when  seemingly  dry,  a  piece  of  the  weighed 
material  was  held  by  tongs  under  the  open  end  of  a  tube  through 
which  the  products  of  combustion  were  made  to  pass.  The  tube 
was  surrounded  by  water  and  when  the  temperature  had  reached 
a  certain  point  the  fire  was  put  out  and  the  weight  of  the  unburned 

1  JUPTNER,  "Lehrbuch  der  Chem.  Tech.  der  Energien,"  vol.  1,  part  I,  p. 
115,  1905. 

2  POOLE,  "The  Calorific  Power  of  Fuels,"  p.  10,  1898. 

3  GROVES  and  THORPE,  "Chemical  Technology"  vol.  1,  p.  360. 

83 


84 


FUEL,  GAS,  WATER  AND  LUBRICATION 


wood  determined.1  Schodler  and  Peterson  in  18362  dried  their 
samples  to  constant  weight,  but  based  their  heat  values  on  the 
weight  of  oxygen  used  in  burning  1  kg.  of  material,  thus  reverting 
to  the  same  principle  as  that  used  by  Berthier. 

Gottlieb  in  18833  used  wood  which  had  been  dried  to  constant 
weight  at  115°C.  His  apparatus  was  of  the  constant  pressure 
type  wherein  the  wood  was  burned  in  a  current  of  oxygen  and 
the  heat  imparted  to  a  known  quantity  of  water.  His  results 
therefore  were  the  most  trustworthy  up  to  that  time  and  do  not 
seem  to  have  been  superseded  by  other  values  since. 

A  series  of  tests  at  the  University  of  Illinois  carried  out  in 
19 164  made  use  of  American  woods  and  had  two  objects  in  view 
(a)  to  determine  the  practicability  of  drying  wood  to  the  moisture- 
free  state  without  alteration  or  loss  of  combustible,  and  (6)  to 
make  careful  heat  determinations  by  use  of  modern  apparatus. 
A  calorimeter  of  constant  volume  with  platinum  lined  bomb  of 
the  Mahler  type  and  adiabatic  insulation  was  employed.  A 
table  of  values  is  given  showing  the  actual  moisture  content 
for  well  seasoned  wood  of  several  varieties,  and  the  heat 
values  calculated  to  both  the  " as-received"  and  the  "dry"  or 
' '  moisture-free  "  basis . 

For  comparison,  the  best  values  in  the  literature  at  the  present 
time,  those  of  Gottlieb,  are  given  in  so  far  as  there  are  corre- 
sponding varieties  of  woods  in  the  two  series  of  results. 
TABLE  X. — HEAT  VALUES  FOR  AMERICAN  WOODS 


Wood 

Moisture 
1  hr.  at 
105°C. 

B.t.u.  "  as- 
received" 

B.t.u. 
"dry  basis" 

Gottlieb 
"oven  dry" 

Differ- 
ence 

Pine  

8.88 

8,050 

8,836 

9  153 

+317 

Oak  
Hickory  
Cherry  

8.35 
10.30 

8.85 

•  7,841 
7,578 
7,860 

8,556 

8,448 
8,623 

8,316 

-240 

Birch..  .  
Poplar.  ..... 

10.18 
10.69 

7,597 
7,716 

8,458 
8,640 

8,586 

+  128 

1  Nicholson's  Journal,  pp.  105,  319,  1813. 

2  Analen  der  Chemic,  vol.  17,  p.  139. 

3  Jour.  Pract.  Chemic,  vol.  28,  p.  412,  1883. 

4  "Calorific  Value  of  American  Woods."     Thesis  for  Master's  Degree  by 
C.  N.  DAVIDSON,  1916. 


CHAPTER  XIV 
PETROLEUM,  DISTILLATES  AND  ALCOHOL 

Use. — The  use  of  petroleum  as  a  fuel  has  greatly  increased  in 
recent  years.  A  number  of  factors  enter  into  the  case.  The 
development  of  the  great  oil  fields  of  Texas,  California  and 
Mexico  brought  in  oils  of  the  heavier  type  with  a  low  percentage 
of  the  lighter  distillates.  In  a  region  where  other  fuels  were 
lacking  these  heavier  oils  went  largely  into  service  for  direct 
burning  as  fuel.  With  the  practice  of  "  topping "  and  the 
extension  of  cracking  processes  to  these  and  the  lighter  oils  a 
residual  by-product  known  as  "fuel  oil"  came  into  extensive  use. 

Output.— Out  of  a  total  annual  output  of  355,000,000  bbl.  in 
the  United  States  in  1918  about  180,000,000  bbl.  were  used  as 
fuel  and  gas  oil.  Of  this  approximately  40,000,000  bbl.  were 
used  for  direct  burning  in  locomotives,  thereby  replacing  sub- 
stantially 10,000,000  tons  of  coal.  The  Navy  used  about 
5,000,000  bbl.  One  hundred  million  barrels  of  gasoline  were 
made  and  20,000,000  bbl.  of  lubricants  were  produced. 

The  chief  factors  to  be  considered  by  the  chemist  are  the 
amount  of  water  present,  the  sulphur  content,  the  heat  value  per 
pound,  and  a  fractional  distillation  showing  the  amount  of 
distillate  over  at  least  three  ranges  of  temperature. 

Water  may  vary  in  amount  from  a  trace  up  to  60  per  cent. 
It  is  determined  by  means  of  the  centrifugal,  diluting  the  sample 
1 : 1  with  gasoline,  or  by  the  usual  fractional  distillation  methods. 

Heat  Values. — For  heat  determination  an  oxygen-bombcalo- 
rimeter  has  the  advantage  that  a  larger  amount,  approximately  1 
gram,  may  be  taken  for  the  test.  Thirty  to  forty  atmospheres 
should  be  used  and  the  bomb  washings  are  especially  adapted 
for  deriving  the  factor  for  sulphur. 

With  the  peroxide  bomb  the  amount  of  oil  is  practically 
limited  to  0.2  or  0.3  gram,  and  the  sulphur  in  the  solution  resulting 
from  the  fusion  is  not  easily  determined  by  photometric  methods 
if  less  than  0.1  per  cent. 

85 


86  FUEL,  GAS,  WATER  AND  LUBRICATION 

A  method  of  calculation  is  in  vogue  based  upon  specific 
gravities,  as  follows:1 

B.t.u.  =  18,650  +  40  (Baume  degrees  -  10) 

The  depletion  of  the  petroleum  supplies  of  the  world  and  the 
great  expansion  in  the  use  of  internal  combustion  engines  puts 
up  to  the  chemist  many  vital  problems  in  the  matter  of  develop- 
ing substitutes  for  petroleum  and  gasoline.  The  internal  com- 
bustion engine  whether  of  the  gas,  gasoline,  or  Diesel  type  has 
developed  a  demand  for  fuels  of  the  mobile  type  and  new  and 
augmented  supplies  of  such  fuel  must  be  continually  forth- 
coming. Heavy-oil  residues  of  such  a  consistency  as  to  be  semi- 
solids  at  reduced  temperatures  are,  by  suitable  mechanical 
appliances,  brought  into  the  field  of  liquid  fuels.  Even  tar,  at 
one  time  considered  impossible  of  such  application,  is  now  a  very 
practical  source  of  heat  both  in  connection  with  steel  furnaces 
and  for  steam  generation. 

Distillates. — As  already  noted  the  gasoline  output  of  the 
United  States  at  the  present  time  is  approximately  100,000,000 
bbl.  Consumption  is  increasing  more  rapidly  than  production. 
In  consequence  new  material  of  low  vaporization  temperature 
is  being  sought  to  augment  the  fuel  supply  of  this  type. 
For  this  purpose  benzene  and  alcohol  are  the  most  promising. 
Casing-head  gasoline  obtained  by  stripping  natural  gas  of  its 
condensable  products  is  also  a  very  considerable  source  of  supply. 
By  mixing  with  heavier  oils  of  the  kerosene  type  and  also  some 
of  the  regular  gasoline  fractions,  a  blended  gasoline  is  made  which 
enters  very  largely  into  the  motor-fuel  supply  of  the  present 
day.  The  method  of  compounding  suggests  the  method  for 
analysis  which  has  been  developed  by  the  U.  S.  Bureau  of 
Mines.2  Compounded  or  synthetic  gasolines  are  variable  in 
composition.  Benzene  recovered  from  coke  oven  gas  has  the 
disadvantage  that  it  freezes  at  5.4°C.  It  mixes  however  in  all 
proportions  with  either  gasoline  or  alcohol,  which  suggest  the 
natural  and  commonly  employed  methods  of  compounding. 

The  range  of  material  involved  in  volatile  liquid  fuel  supplies 
is  thus  seen  to  be  a  very  wide  one,  with  consequent  variation  in 

1  SHERMAN  and  KROPFF,  Jour.  Am.  Chem.  Soc.,  vol.  30,  p.  1626. 

2  DEAN,  E.  W.,  U.  S.  Bureau  of  Mines,  Tech.  Paper  166,  1917. 


PETROLEUM,  DISTILLATES  AND  ALCOHOL  87 

heat  value.  It  is  evident  that  the  determination  of  calorific 
values  becomes  an  important  feature.  About  the  only  difficulty 
to  be  encountered  results  from  the  volatility  of  some  of  the 
material  to  be  worked  with. 

In  determining  the  calorific  values  of  highly  volatile  substances 
some  special  procedure  must  be  observed  for  avoiding  loss  in 
weighing  out  the  sample  or  in  preparing  the  charge. 

A  container  for  the  volatile  liquid  may  be  made  in  the  form  of  a 
very  thin- walled  glass  bulb  of  about  1  cm.  diameter  and  having  a 
short  capillary  stem  of  2  or  3  cm.  These  are  readily  prepared  by 
the  analyst  from  soft-glass  tubing  which  has  been  drawn  out 
into  a  capillary  1  or  2  mm.  in  diameter.  By  softening  the  end 
of  such  a  capillary  in  the  flame,  it  may  be  blown  into  a  small  bulb 
of  suitable  size.  Such  a  bulb  may  be  filled  by  warming  the 
weighed  bulb  and  immersing  the  capillary  in  the  liquid  to  be 
analyzed.  By  contraction  of  the  air  a  small  amount  of  the 
liquid  is  drawn  into  the  bulb,  and  by  repeating  the  process  the 
bulb  may  be  filled  to  any  desired  extent.  It  is  then  sealed  and 
weighed.  Bulbs  of  this  sort  should  be  used  with  either  the 
oxygen  bomb  or  sodium  peroxide  calorimeter.  With  heavier  or 
slightly  volatile  oils  they  are  not  necessary.  When  used  in  the 
oxygen  bomb  the  bulb  with  the  volatile  liquid  should  be  placed 
in  the  bottom  of  a  10  cc.  platinum  or  Illium  crucible  and  the  fuse 
wire  wrapped  two  or  three  times  around  the  capillary  stem.  The 
heat  of  the  current  will  be  sufficient  to  rupture  the  bulb  and, 
being  discharged  at  the  bottom  of  the  crucible,  the  vapors  must 
rise  and  flow  over  the  edge  in  the  process  of  combustion.  In  the 
case  of  the  sodium  peroxide  bomb,  the  glass  bulb  is  placed  so 
that  it  rests  on  the  bottom  of  the  fusion  cup  and  is  covered  com- 
pletely by  the  chemical.  Just  before  closing  the  cup,  the  bulb  is 
broken  by  means  of  a  glass  rod  pressed  downward  in  such  a 
manner  as  to  rupture  the  bulb.  The  cover  is  then  at  once 
fastened  in  position  and  the  contents  shaken  thoroughly  for 
uniform  mixing.  In  this  manner  highly  volatile  liquids  may  be 
handled  in  either  type  of  instrument. 

Alcohol. — Volatile  fuels  of  the  hydrocarbon  type  may  increase 
in  cost  to  a  point  where  alcohol  may  enter  the  field  as  a  competi- 
tor. It  is  even  now  receiving  considerable  attention  because  of 
certain  inherent  properties  when  used  in  internal  combustion 


88  FUEL,  GAS,  WATER  AND  LUBRICATION 

engines.  In  mixtures  with  hydrocarbons  it  promotes  a  more 
efficient  combustion  and  has  the  added  advantage  that  it  carries 
into  the  combustion  chamber  a  certain  ratio  of  water  vapor 
which  serves  as  a  protective  medium  for  the  hydrocarbons, 
reducing  their  tendency  toward  decomposition  or  cracking  and 
the  consequent  deposition  of  carbon.  While  alcohol  has  no  ash 
it  has  a  large  percentage  (34.8)  of  combined  oxygen  which 
approximately  represents  the  inert  material.  It  was  formerly 
denatured  by  adding  0.5  per  cent  of  benzine  and  10  per  cent  of 
methyl  (wood)  alcohol  to  make  it  poisonous  and  not  easily 
purified  by  re-distilling.  This  is  known  as  formula  No.  1  (now 
suspended).  Methyl  alcohol  is  at  the  present  time  practically 
all  absorbed  in  the  manufacture  of  formaldehyde,  extensively 
used  as  an  anti-smut  reagent  in  the  treatment  of  grain. 

The  U.  S.  Bureau  of  Internal  Revenue  has  published1  four 
complete  and  33  special  formulas.  The  former  are  allowable 
for  any  use  desired,  while  the  latter  are  usable  only  under  special 
regulations  for  specific  purposes.  The  completely  denaturing 
formulas  use  a  small  amount  of  methyl  alcohol,  not  exceeding 
2  per  cent,  and  pyridine  bases  1  per  cent.  Other  variations 
prescribe  benzol,  |  per  cent,  benzine  (kerosene),  0.5  per  cent, 
etc. 

From  the  fuel  standpoint,  formula  No.  3  is  the  most  interesting, 
as  follows: 

Ethyl  alcohol 100  parts  by  volume 

Ethyl  ether 5  parts  by  volume 

Benzine 2  parts  by  volume 

Pyridine 1  part  by  volume 

1  Regulation  61,  p.  97. 


CHAPTER  XV 
FUEL  GAS 

Types. — The  gas  industry  was  originally  developed  as  a 
lighting  proposition.  With  the  advent  of  electricity  it  began  to 
take  second  place  in  that  field.  Today  the  industry  is  in  a 
transition  stage  with  the  logic  of  events  clearly  pointing  to  the 
ultimate  utilization  of  gas  substantially  as  a  fuel.  The  advent 
of  natural  gas  has  doubtless  been  a  factor  also  in  the  change, 
at  least  by  way  of  illustration  as  to  the  advantages  of  fuel  in  the 
gaseous  form.  The  use  of  natural  gas  has  increased  in  the  last 
35  years  from  an  annual  production  of  less  than  50,000,000,000 
to  over  900,000,000,000  cu.  ft.  The  total  yield  of  gas  from 
all  sources  in  1917  was  approximately,  1,450,000,000,000  cu.  ft. 
and  of  this  222,000,000,000  or  15  per  cent  were  supplied 
to  domestic  users.  Of  this  probably  not  over  20  per  cent  or 
3  per  cent  of  the  total  was  used  for  lighting  purposes.  Other 
factors  also  enter  into  the  case.  Over  75  per  cent  of  the  gas 
supplied  to  cities  at  the  present  time  is  so  called  water-gas  which, 
because  of  candlepower  requirements,  must  be  carbureted  with 
gas  oil.  With  an  average  of  3  gal.  of  such  oil  used  for  1,000  cu. 
ft.  of  gas  made,  the  manufacturing  cost  per  thousand  feet  with 
oil  at  10  cents  a  gallon  approaches  very  nearly  to  the  selling  price. 
For  these  and  attending  reasons  the  public  is  gradually  realizing 
that  candlepower  and  expensive  oil  for  carbureting  go  together, 
and  that  a  gas  with  less  luminosity  can  be  made  at  a  much  lower 
price.  The  uncertain  and  diminishing  supply  of  gas  oil  adds  to 
the  argument  for  abandoning  the  candle  power  standard  so  that  a 
decided  trend  is  evident  toward  the  heat  unit  basis  and  a  lowering 
of  the  requirement  in  that  particular  from  600  B.t.u.  per  cubic 
foot,  which  was  formerly  a  very  nearly  universal  standard.  The 
ultimate  standard  when  settled  upon  will  doubtless  bear' some 
relation  to  the  number  of  heat  units  carried  by  the  uncarbureted 
gas. 

89 


90 


FUEL,  GAS,  WATER  AND  LUBRICATION 


TABLE   XI. — TYPICAL  COMPOSITION  OP  THE  MORE  COMMON  FUEL  GASES 
Assembled  from  various  sources 


Types  of  gas 

CO2 

02 

Illuminants 

H2 

CO 

Paraffins 

N2 

Gross 
B.t.u. 

C2H4 

CrtH6 

CH4 

C2H6 

Natural 

0.2 
0.5 
2.5 
4.0 

5.4 
2.9 

0, 
0.5 
0.3 
0.5 

1  1 
0.5 

1.4 

0.8 

0.3 
4. 
3 

0 
10.0 
35 

4 

1.5 
0.4 


0 
4 

9 
4.5 
00 
6 

1.6 

1.6 
46.0 
52.3 
45.7 

41.9 
27.9 
4.5 
46.6 

47.3 
12.0 

0.4 
6.0 
10.7 
45.8 

34.0 
25.3 
0.5 
7.1 

4.3 
27.0 
25.5 

94.1 
40.0 
26.9 
2.0 

7.5 
25.9 
60 
33 

33.2 
2.5 

.00 
.20 

4.5 

3.0 
3.0 
3.9 

2.0 

9.2 
3.0 

5.4 

2.9 
55.6 
61.5 

970 
670 
552 
322 

335 
765 
1,500 
660 

670 
157 

87 

Coal  gas  (horizontal  retorts)  . 
Coal  gas  (vertical  retorts)  .  .  . 
Water  gas  (from  coke) 

Water  gas  (from  bituminous 
coal).      . 

Carbureted  water  gas 

Pintsch  .  . 

By-product  oven  (Koppers)  . 
Low-temperature  carboniza- 
tion below  800°C 

1.7 

3.9 
2  5 

Producer  

Blast  furnace  

12.7 

0.3 

With  the  exhaustion  of  our  natural  gas  supplies  and  the  modifi- 
cations in  the  standard  requirements  for  house  use  now  taking 
place,  it  is  evident  that  the  production  of  the  future  will  come  in 
the  main  from  installations  of  the  by-product  oven  type  and  from 
generators  of  the  water  gas  type,  using  either  coke  or  raw  coal. 
Problems  of  manufacture  and  purification,  standards  of  quality, 
and  methods  of  analysis  can  not  be  elaborated  in  this  connection. 
Brief  reference  should  be  made  however  to  methods  for  determin- 
ing heating  values. 

Heating  Value  of  Gas. — Calorimeters  for  determining  the 
heating  value  of  gases  are  of  the  intermittent  and  of  the  con- 
tinuous flow  type. 

Hempel1  makes  use  of  an  apparatus  which  burns  a  volume 
of  gas  in  an  atmosphere  of  oxygen,  the  heat  being  imparted  to  a 
known  amount  of  water.  By  repeating  the  process  using  hydro- 
gen under  the  same  conditions  as  to  volume  and  the  amount  of 
water  heated,  and  reducing  the  temperature  readings  to  the 
same  temperature  and  pressure,  the  value  of  the  unknown  gas  is 
found  by  a  direct  ratio,  using  an  accepted  value  for  hydrogen  at 
standard  conditions  of  temperature  and  pressure. 

1  HEMPEL'S  "Gas  Analysis,"  3d  ed.,  p.  437. 


FUEL  GAS 


91 


The  author1  made  use  of  two  calorimeters,  Fig.  20,  in  parallel 
burning  equivalent  volumes  simultaneously  of  hydrogen  and 
the  unknown  gas  under  identical  conditions  as  to  temperature 


FIG.  20. — Parr  no n- continuous  gas  calorimeter. 


and  pressure.  Compensations  for  humidity  of  the  air  and 
barometric  pressure  were  therefore  self-adjusting,  and  since 
equivalent  volumes  were  burned  the  amount  was  not  essential, 
hence  a  meter  was  unnecessary. 

1  Jour.  Ind.  and  Eng.  Chem.  vol.  2,  p.  337,  1910. 


92  FUEL,  GAS,  WATER  AND  LUBRICATION 

In  the  original  testing  out  of  this  instrument  in  comparison 
with  one  of  the  Junker  type  a  constant  difference  was  observed 
wherein  the  latter  gave  lower  results  of  from  3  to  8  B.t.u.  per 
cubic  foot.  The  suggestion  was  made  at  the  time1  that  the 
discrepancy  was  due  to  variations  in  the  humidity  of  the  air  and 
the  fact  that  the  Junker  instrument  did  not  make  note  of  it. 
This  possibility  was  verified  by  the  Committee  on  Calorimetry 
of  the  American  Gas  Institute.2 

Following  the  recommendations  in  that  report,  it  has  become 
the  practice  to  correct  for  humidity  as  well  as  barometric  pres- 
sure and  temperature. 

Although  instruments  of  the  non-continuous  type  have 
certain  advantages,  such  as  the  ability  to  operate  on  relatively 
small  samples,  they  lack  the  advantage  of  continuous  flow  and 
the  opportunity  of  taking  readings  at  any  time.  Indeed  the 
trend  of  development  in  the  matter  of  determining  the  heating 
value  of  combustible  gases  must  inevitably  be  toward  an  instru- 
ment which  will  make  continuous  record  of  the  quality  of  the 
output. 

Flow  Calorimeters. — The  continuous  flow  calorimeter  most 
commonly  in  use  is  of  the  Junker  type.3 

The  instrument  is  shown  in  Fig.  21. 

The  gas  is  conducted  through  a  wet  meter,  then  preferably 
through  a  pressure  equalizer,  after  which  it  goes  to  a  Bunsen 
burner.  The  products  of  combustion  give  up  their  heat  to 
water  under  exact  control  as  to  temperature  and  mass.  There 
are  specific  modifications  to  be  made  including  temperature  cor- 
rections for  both  the  barometer  and  the  meter  readings,  also  for 
variations  in  temperature  between  the  inlet  water  and  that  of  the 
room,  as  well  as  for  the  humidity  of  the  air. 

From  prepared  tables  (see  Appendix,  Table  IV)  are  found  the 
correction  factors  to  be  applied  to  the  meter  readings  to  give 
equivalent  volumes  at  60°F.  and  30  in.  of  mercury.  After 
applying  calibration  corrections  for  inlet  and  outlet  water 
temperature  readings  the  true  rise  in  temperature  of  the  water 

lLoc.  cit. 

2  Report  of  the  Committee  on  Calorimetry  for  the  Seventh  Annual  Meet- 
ing, 1912. 

3  JUNKER,  HUGO,  Jour,  fur  Gasbel,  vol.  36,  p.  81,  1898. 


FUEL  GAS  93 

is  obtained  which,  with  the  reduction  of  gas  volume  and  weight 
of  the  water,  gives  the  essential  factors  for  substituting  in  the 
formula: 

Mass  (t1  -  0 
Heat  value  =  ^^r 


Volume  in  cubic  feet 


If  the  mass  is  expressed  in  pounds,  t  in  degrees  Fahrenheit,  and 
V  in  cubic  feet,  the  result  will  be  B.t.u.'s  per  cubic  foot. 


FIG.  21.  Junker  continuous  flow  calorimeter. 

A  factor  for  radiation  changes  is  also  applied  where  there  is  a 
difference  between  the  inlet  water  and  that  of  the  room.  This 
factor  may  be  found  in  Table  XII.  The  correction  is  added  if 
the  inlet  water  is  warmer  than  the  air  of  the  room  and  subtracted, 
if  colder. 


94 


FUEL,  GAS,  WATER  AND  LUBRICATION 


TABLE    XII.1 — CORRECTIONS    FOR    DIFFERENCE   BETWEEN    INLET-WATER 

TEMPERATURE  AND  ROOM  TEMPERATURE 

Used  with  the  Junker  calorimeter 


Room  temperature, 
degrees  Fahrenheit 

Corrections  in  B.t.u.  per  1°F. 

For  calculating 
total  heating  value 

For  calculating 
net  heating  value 

50 

0.5 

0.4 

60 

0.6 

0.4 

70 

0.7 

0.4 

80 

0.8 

0.4 

90 

0.9 

0.5 

100 

1.0 

0.5 

High  and  Low  Heat  Values  for  Combustible  Gases. — For 
purposes  of  standardization  of  output  and  control,  it  is  generally 
conceded  that  the  high  or  total  heating  value  is  the  more  logical 
standard  of  reference.  However,  for  many  technical  appli- 
cations, especially  in  the  use  of  gas  for  internal  combustion 
engines  where  all  of  the  products  of  combustion  are  delivered 
above  100°C.,  the  net  or  low  heat  values  are  the  most  significant. 

In  the  Junker  type  of  instrument  the  water  of  condensation 
from  the  combustion  of  the  gas  is  measured.  The  number  of 
cubic  centimeters  per  cubic  foot  multiplied  by  0.600  will  give 
the  heat  in  calories  which  would  be  required  to  vaporize  the  water 
condensed.  The  amount  of  condensed  water  therefore  in  cubic 
centimeters,  multiplied  by  3.968  X  0.600  will  give  the  amount 
of  heat  in  B.t.u.  to  be  subtracted  from  the  total  heat  to  give  the 
net  heat  value. 

Ammonia  and  Sulphur. — Ordinarily  a  limit  of  5  grains  of  am- 
monia per  100  cu.  ft.  of  gas  is  prescribed.  The  need  for  any 
special  attention  to  this  impurity  does  not  often  occur,  however, 
since  the  ammonia  is  easily  removed  and  has  a  value  which 
makes  its  recovery  profitable.  Its  presence,  moreover,  is  in- 
jurious to  gas  meters.  Sulphur  occurs  in  manufactured  gas 
mainly  as  hydrogen  sulphide,  H2S.  Carbon  and  hydrocarbon 
compounds  of  sulphur  are  usually  present,  but  in  much  smaller 
amount.  In  coal  gas,  ordinarily  about  56  of  these  compounds 
are  carbon  bisulphide  and  the  remainder  are  thiophens  and  mer- 

1  From  U.  S.  Bureau  of  Standards  Circular  48. 


FUEL  GAS  95 

captans.  It  is  not  easy  to  prescribe  a  limit  for  sulphur,  owing  to 
the  wide  variations  both  in  operating  ^conditions  and  in  the 
type  of  materials  which  must  be  used  in  gas  manufacture.  The 
Bureau  of  Standards1  recommends  a  limit  of  30  grains  of  total 
sulphur  per  cu.  ft.  of  gas.  Whatever  the  form  in  which  sulphur 
occurs,  in  the  process  of  combustion  it  burns  to  862  and  S03. 
The  presence  of  more  than  a  trace  of  H2S  shows  carelessness  in 
the  manufacturing  process. 

Apparatus  for  the  Analysis  of  Fuel  Gases. — To  meet  the  con- 
ditions of  analysis  for  the  constituents  found  in  fuel  gases,  it  is  of 
great  advantage  to  have  assembled  as  permanent  equipment  in 
the  laboratory  a  unit  outfit  capable  of  determining  all  the  con- 
stituents usually  found  in  a  fuel  gas.  Investigational  studies, 
especially,  have  been  materially  advanced  as  a  result  of  greatly 
improved  apparatus  for  carrying  out  the  analysis  of  combustible 
gases,  especially  those  of  the  type  devised  by  Col.  G.  A.  Burrell.2 
For  laboratory  use  where  portability  is  not  an  essential  feature, 
such  an  installation  combining  all  of  the  features  for  carrying  out 
the  processes  will  be  found  exceedingly  convenient  and  satis- 
factory. The  development  of  this  type  of  instrument  has 
greatly  simplified  the  processes  involved.  For  control  work  and 
the  usual  technical  analysis  of  gases,  the  apparatus  as  used  in  the 
author's  laboratory  is  shown  in  Fig.  22  and  Fig.  44.  It  does  not 
differ  in  any  essential  feature  from  the  Burrell  apparatus  except 
that  a  saturated  salt  solution  is  used  in  the  leveling  tube,  and 
for  greater  convenience,  a  companion  tube  for  leveling  is  con- 
nected to  the  gravity  tube  by  a  Y  with  a  stop  cock  in  the  main 
connection  below  the  Y,  and  another  at  the  top  of  the  equalizing 
tube. 

Analysis  of  Fuel  Gas. — The  analysis  of  fuel  gas  makes  use  of 
methods  of  absorption  and  combustion. 

1.  Carbon  dioxide  is  absorbed  in  a  solution  of  100  grams  KOH 
in  150  cc.  of  water.     The  reagent  may  be  used  until  it  approaches 
the  point  of  saturation,  indicated  by  the  slowing  up  of  the 
reaction. 

2.  Oxygen  is  absorbed  by  an  alkaline  solution  of  pyrogallol. 

1  Standards  for  Gas  Service,  Circular  32,  p.  101,  1915. 

2  JONES  and  NEUMEISTER,  An  improved  Orsat  apparatus  for  gas  analysis: 
U.  S.  Bureau  of  Mines,  Bull.  92 ;  Chem.  and  Met,  vol.  21,  p.  734,  1919. 


96  FUEL,  GAS,  WATER  AND  LUBRICATION 


FIG.  22. — Modified  Orsat  apparatus  for  analyzing  gases. 


FUEL  GAS  97 

The  usual  mixture  is  1  part  of  KOH  with  2  parts  of  water,  and 
this  solution  mixed  in  equal  volumes  of  pyrogallol  solution,  made 
by  dissolving  1  part  of  pyrogallol  in  3  of  water.  According  to 
Professor  White,1  the  solution  may  not  be  used  with  safety 
beyond  an  absorption  of  about  8  volumes  of  oxygen  to  1  volume 
of  solution  on  account  of  the  formation  of  carbon  monoxide  in 
the  reaction. 

3.  Ethylene  is  absorbed  in  a  solution  of  bromine  in  water. 
If  a  few  drops  of  bromine  are  kept  in  the  pipette  all  the  time, 
this  reagent  may  be  used  indefinitely.     After  the  absorption  of 
the  ethylene  has  been  completed,  it  is  necessary  to  pass  the  gas 
into  the  KOH  pipette  to  remove  the  bromine  that  has  vaporized. 

4.  Benzene   is   absorbed  in  a  solution  of  15  to  20  per  cent 
fuming  sulphuric  acid.     This  reagent  need  not  be  renewed  as  long 
as  it  fumes  readily,  indicating  the  presence  of  free  S03.     As 
with  the  bromine,  so  must  the  S03  be  removed  by  passing  the 
gas  back  into  the  KOH  pipette. 

5.  Hydrogen  and  Carbon  Monoxide   are  determined  by  the 
method  of  fractional  combustion  as  suggested  by  the  work  of 
Campbell.2    He  found  the  combustion  point  for  gases  in  contact 
with  pure  copper  oxide  to  be  as  follows: 

TABLE  XIII. — COMBUSTION  TEMPERATURES  FOR  GASES  IN  CONTACT  WITH 

COPPER  OXIDE 


Gas 

Reacting  temperatures  with  pure  CuO, 
degrees  Centigrade  (CAMPBELL) 

CO 

100  to  105 

H2  

175  to  180 

C3H6 

270  to  280 

C2H4 

315  to  325 

C4H8  

320  to  330 

CH4      . 

650  to  750  in  air3 

The  low  range  of  temperatures  for  carbon  monoxide  and 
hydrogen  compared  with  marsh  gas  has  been  made  the  basis  for  a 
method  of  fractional  combustion,  whereby  the  two  low-burning 

1  WHITE,  A.  H.,  "Technical  Gas  and  Fuel  Analysis,"  p.  34,  1920. 

2  Am.  Chem.  Jour.,  vol.  17,  p.  688,  1895.      See  also  JAGER,  Jour.  Gasbe- 
leucht,  vol.  41,  p.  764,  1898. 

3  DIXON  and  COWARD,  Jour.  Chem.  Soc.,  vol.  95,  p.  519,  1909. 
7 


98  FUEL,  GAS,  WATER  AND  LUBRICATION 

gases  are  removed  without  affecting  the  paraffins.  Since  the 
hydrogen  in  burning  to  water  disappears,  the  contraction  repre- 
sents the  H2,  and  since  the  CO  burns  to  CC>2,  each  volume  of  CC>2 
indicated  from  absorption  in  the  KOH  solution  represents  one 
volume  of  CO. 

The  combustion  takes  place  most  satisfactorily  by  maintaining 
the  copper  oxide  at  about  300°C.  After  the  combustion  has 
been  completed,  it  is  necessary  to  sweep  out  the  tube  containing 
the  CuO  with  pure  nitrogen  to  remove  the  gas  being  analyzed 
and  any  CO2  formed. 

6.  Methane  and  any  remaining  hydrocarbons  of  the  paraffin 
series  are  determined  by  the  method  of  slow  combustion  over 
mercury.  The  method  of  Coquillon  (1876),  who  first  made  use 
of  the  platinum  spiral,  has  received  its  best  development  from 
Professor  L.  M.  Dennis.1  One  of  the  main  objections  to  the 
method  has  been  the  tendency  toward  the  formation  of  oxides 
of  nitrogen,  resulting  from  the  incandescent  spiral.  Dennis  and 
Hopkins2  propose  to  obviate  this  difficulty  by  use  of  pure  oxygen 
instead  of  air. 

The  methods  thus  indicated  under  (5)  and  (6)  for  determining 
the  various  combustibles  are  especially  provided  for  in  the  appa- 
ratus as  shown,  Fig.  22.  It  will  be  noted  that  there  are  no 
complications  involved  in  developing  the  volumes  for  hydrogen 
and  carbon  monoxide  as  discussed  under  (5).  To  deduce  the 
volumes  for  the  mixed  hydrocarbons  of  the  paraffin  type  as 
under  (6)  is  somewhat  more  involved.  However,  the  matter  is 
simplified  in  that  all  of  the  constituents  have  been  removed  at 
this  stage  excepting  the  paraffins  and  nitrogen.  Then  while  a 
mixture  of  combustible  gases  remains,  it  consists  of  a  homologous 
series,  which  is  of  material  aid  in  devising  a  method  of  compu- 
tation— for  arriving  at  the  original  volume. 

Computation  of  Volume  of  Paraffins  from  Analytical  Data.— 
After  the  process  of  burning  the  paraffin  gases,  four  values  are 
available  upon  which  to  base  the  calculations.  (1)  The  volume 
of  the  sample  employed.  (2)  The  volume  of  the  oxygen  used. 
(3)  The  volume  of  the  resultant  gas  after  combustion.  (4)  The 
volume  of  carbon  dioxide  in  the  resultant  gas. 

1  DENNIS,  L.  M.,  "Gas  Analysis,"  p.  147,  1913. 

2  Jour.  Am.  Chem.  Soc.,  vol.  21,  p.  398,  1899. 


FUEL  GAS  99 

By  subtracting  (3)  from  the  sum  of  (1)  and  (2),  the  contraction 
due  to  the  condensation  of  water  formed  from  the  combustion 
of  the  combined  hydrogen  is  obtained,  and  from  this  contraction, 
and  the  volume  of  carbon  dioxide  formed,  can  be  calculated  the 
volume  of  the  paraffin  hydrocarbons  in  the  original  sample  of  gas. 
Also  the  index  of  the  average  composition  of  the  paraffins  can  be 
determined. 

0/^1     C*f) 

The  formula  for  determining  the  volume  is:  V  =  -    —^~ 

fT) 

and  for  the  index  of  the  average  composition  is:  n  =  ~^~-     The 

derivation  is  as  follows: 

(a)  CnH2n+  2  +  ^^O,  ->  nC02  +  (n  +  1)H2O 

From  (a)  the 

contraction  is  (<*      \    -i\v 

determined  as  (6)      C  =  V  +  —:  -  nV 


2 

From  (6) (c)    nV  =  2C  -  37 

also  from  (a) .  .  (d)  nV  =  C02 
By  solving  the 
two     equations 
(c)and(d) (e)     7  = 


c  =  27  4-  3n7  +  7  -  2nV 
C 


2 

nV  +  37 


3 
rrL 

Then  from  (d).  .(/)      t 


C02 


The  value  7  is  the  correct  volume  of  the  hydrocarbon  gas  no  mat- 
ter how  many  of  the  homologues  are  present  and  in  like  manner  the 
value,  n,  is  the  average  composition  of  the  mixture.  If  methane 
was  the  only  homologue  present,  the  value  for  n  would  be  unity. 
Also  if  ethane  was  the  only  constituent  the  value  of  n  would  be 
2.  This  may  be  proven  by  solving  for  n  from  the  equations 


CH  4+  202  -*  C02  +  2H20  n  =  }  VO!'  =  1.00 

1    VOl. 


and  2C2H6  +  7O2->  4C02  +  6H2O  n  =  <1  =  2.00 

Z  vol. 


100 


FUEL,  GAS,  WATER  AND  LUBRICATION 


It  is  very  seldom  that  a  value  for  n  of  more  than  2  is  obtained  and 
though  this  does  not  mean  that  there  are  none  of  the  homologues 
higher  than  ethane  present  in  the  gas,  it  does  show  that  methane 
and  ethane  predominate.  The  volume  of  hydrocarbons  is 
usually  considered  as  being  only  methane  and  ethane  and  is 
differentiated  into  these  two  by  applying  the  portion  of  n  greater 
than  unity  as  a  factor  which  when  taken  times  the  volume  V 
will  give  the  volume  of  ethane.  Methane  will  then  be  V  minus 
ethane  and  the  volumes  of  these  two  constituents  as  determined 
will  be  reported  in  per  cent  on  the  basis  of  the  original  sample  of 
gas. 

The  difference  between  the  sum  of  all  the  constituents  so  far 
determined  and  the  original  100  cc.  of  sample  is  considered  as 
nitrogen.  Then  of  necessity  the  nitrogen  value  must  contain 
the  total  error  of  the  several  determinations. 

An  analysis  of  a  sample  of  gas  from  a  low-temperature  carboni- 
zation test  on  Illinois  coal  follows : 

GAS  SAMPLE  No.  175-2 
Illustrating  the  calculations  for  the  paraffins 


Constituents 

Volume, 
100  cc. 

Per  cent 

Calculations 

CO2 

95  4 

4  6 

O2  

94  5 

0.9 

C2H4 

90  1 

4.4 

C6H6  

89  2 

0.9 

H2     

43  9 

45.3 

New  volume 

70  1 

PO 

fii   ^ 

8  8 

„      2C  -  CO2                 CO2 

V  —                           inn  n 

O2  added 

156  0 

Total 

O1  7    Q 

.0  —  dd.4 

After  combination  .  .  . 

ZLi  .0 

151.5 

3 

Q8  2 

• 

„          V0.6        ^9    . 

Contraction  

65  8 

'•m»       Q      .."*»* 

CO2  formed 

QQ   4. 

0 

Thenn  =  f44  =1-031 

CH4  

31.4 

32.4 

C2H6           

1.0 

And  oZ.4  XU.Uol  —  l.U  CC.   V^2*l6 

N2  

2.7 

Total  

100.0 

FUEL  GAS 


Heat  Values  by  Calculation.  —  It  will  be  seen  from  the  fore- 
going that  with  an  apparatus  which  compares  favorably  with  a 
calorimeter  in  the  matter  of  facility  and  speed  of  operation,  the 
method  of  obtaining  heat  values  for  combustible  gases  by  analysis 
and  calculation  is  given  a  very  much  more  favorable  status.  This 
development  will  appeal  especially  to  those  interested  in  gas 
engine  work  where  exact  determinations  for  the  low  or  net  heat 
values  are  desired  and  which  require  for  their  satisfactory  deri- 
vation an  analysis  of  the  gas. 

The  gross  and  net  heat  values  in  B.t.u.  for  a  number  of  differ- 
ent gases  are  given  in  Table  XIV  and  since  the  values  for  all  the 
combustible  gases  found  in  the  foregoing  analysis  are  included, 
it  is  possible  to  calculate  with  a  good  degree  of  accuracy  the 
heat  value  of  the  original  gas  sample.  The  heat  values  given 
are  for  standard  conditions,  60°F.  and  30  in.  of  mercury,  and 
since  the  per  cents,  as  determined,  hold  for  the  gas  under  any 
temperature  and  pressure  condition,  all  that  is  necessary  in  calcu- 
lating the  total  heat  value  of  the  sample  is  to  obtain  a  summation 
of  the  per  cents  of  the  combustible  constituents  times  their 
respective  heat  values.  Thus  we  may  calculate  the  gross  B.t.u., 
from  the  values  in  the  table,  in  the  following  manner: 
TABLE  XIV.  —  HEAT  OF  COMBUSTION  FOR  THE  MORE  COMMON  GASES 


Gross 

Gross 

Gross  values3 

. 

Gas 

Formula 

values1  cal- 
ories per 
gram  mole- 

values B.t.u. 
per  cubic  foot 
at  60°,  30  in. 

Net  values2 
B.t.u.  per 
cubic  foot 

B.t.u.  per 
cubic  foot  at 
60°,  30  in.  cal- 
culated from 

cule 

mercury 

net  value 

Hydrogen  

H2 

68  ,  360 

326.2 

271.8 

320.9 

Carbon  monoxide.  . 

CO 

67  ,  960 

323.5 

320.9 

321.0 

Methane  

CH4 

211,930 

1,009.0 

908.5 

997.9 

Ethane  

C2H6 

370,440 

1,764.4 

1  ,  604  .  0 

1,688.7 

Propane 

CsHs. 

529,210 

2,521.0 

Butane 

C4HiC 

687  ,  190 

3,274.0 

Ethylene 

C2H4 

333,350 

1  ,  588  .  0 

1,511.4 

1  ,  590  .  6 

Propylene  

C3H6 

492,740 

2  ,  347  .  2 

Butylene  

C4H8 

650  ,  620 

3,099.12 

Acetylene  

C2H2 

310,050 

1,476.7 

1,424.4 

1,486.4 

Benzene  (vapor)  .... 

CeHe 

799,350 

3,807.5 

3,571.5 

3,634.0 

1  WHITE,  A.  H.,  "  Technical  Gas  and  Fuel  Analysis,"  p.  301,  1920.     Gross  values;  tempera- 
ture of  products  of  combustion  being  reduced  to  64.4°F. 

2  FELBECK,   GEORGE    T.,   Thesis:    "A   Mathematical   Determination   of  the   Maximum 
Pressure  and  the  Extent  of  Combustion  in  the  Gas  Engine."     Univ.  of  111.,  1921. 

3  Gross  values  calculated  from  "Felbeck's  Net  Values,"  using  formula  as  proposed  by 
Goodenough,  G.  A.,  Professor  of  Thermodynamics,  University  of  Illinois. 


1Q2  ;  !  ;       ^FuEL,  GAS,  WATER  AND  LUBRICATION 


GAS  SAMPLE  No.  175-2 
Calculation  of  total  heat  value 


COMBUSTIBLE 
CONSTITUENT 


C2H4.. 
C6H6.. 

H2 

CO.... 
CH4... 
C2H6.. 


PER  CENT  BY                                                     RESULTING  HEAT 
ANALYSIS              ACCEPTED  B.T.U.                   VALUE 

4.4 

X 

1,588.0 

69.9 

0.9 

X 

3,807.5 

34.3 

45.3 

X 

326.2 

147.8 

8.8 

X 

323.5 

28.5 

31.4 

X 

1,009.0 

316.8 

1.0 

X 

1,764.5 

17.6 
614.9 

The  values  above  are  the  usually  accepted  heating  values  for  the 
several  constituents,  and  may  be  found  in  most  texts  and  hand- 
books on  this  subject.  They  represent  the  high  or  gross  values 
since  the  determinations  were  carried  out  at  room  temperature. 
As  previously  mentioned,  the  net  or  low-heating  value  of  a  gas 
is  often  desired  and  Table  XIV  includes  these  values  for  the 
various  constituents.  There  is  also  given  a  second  set  of  gross 
values  which  have  been  calculated  from  these  net  values.  There 
are  some  arguments  in  favor  of  proceeding  from  the  net  values 
as  a  basis  and  from  such  values,  derive  the  high  or  gross  factors. 
Calculations  thus  made  on  the  particular  sample  above  referred 
to  show  results  as  follows :  comparison  being  made  with  the  indi- 
cated results  from  a  Junker  calorimeter. 

NET  OR  Low       GROSS  OR  HIGH 
Determined  by  Junker 

~  _0       calorimeter 554.4  620.0 

Gas  sample  No.  175-2  614  Q2 

Calculated 551. 31  606. 53 

In  case  the  question  is  raised  as  to  the  presence  of  higher 
homologues  of  the  paraffins  which  might  influence  the  heating 
value,  it  is  well  to  note  that  the  value  V  (w(757)  +  251), 4  derived 
from  the  heat  of  combustion  of  C  and  H  in  CnH2w+2,  will  give  the 
gross  value  in  B.t.u.'s  for  the  total  paraffins  in  the  sample.  In 
this  case  32.4  (1.031  (757)  +  251)  =  334.2  B.t.u.,  while  the  sum 

1  Calculated  from  analytical  data  using  net  values,  from  Table  XIV. 

2  Calculated  from  analytical  data  using  gross  values  as  found  in  handbooks. 

3  Calculated  from  analytical  data  using  gross  values  from  Table  XIV, 
derived  from  net  values. 

4  EARNSHAW,  E.  W.,  Water  gas:  Jour.  Franklin  Inst.,  vol.  146,  pp.  161- 
176. 


FUEL  GAS  103 

of  the  heat  values  for  methane  and  ethane  as  calculated  from  their 
per  cents  is  334.4.  This  shows  the  possibility  of  calculating 
the  gross  values  for  the  paraffins  without  differentiating  into  the 
homologues,  and  in  cases  where  it  is  impossible  to  differentiate, 
as  where  n  is  greater  than  2,  it  is  still  quite  possible  to  obtain  the 
correct  heating  value  of  the  gas  by  applying  the  above  formula. 
NOTE. — One  rather  remotely  possible  source  of  error  in  calcu- 
lating the  B.t.u.  from  the  analytical  results  as  obtained  might  be 
mentioned  and  that  is,  in  the  case  of  higher  homologues  of  the 
olefin  series  or  other  unsaturated  hydrocarbons,  and  as  there  is 
no  way  of  determining  or  differentiating  these,  this  possible  error 
is  beyond  control.  However,  it  is  not  probable  that  unsaturated 
compounds  other  than  ethylene  often  occur  in  the  gases  analyzed, 
and  errors  from  this  source  would  doubtless  be  less  than  the 
experimental  errors  incident  to  the  processes  involved. 


CHAPTER  XVI 
FLUE  GAS 

Gas  Volumes. — Air  has  the  composition  by  volume  of  20.78  per 
cent  of  oxygen  and  79.22  per  cent  of  nitrogen.  In  passing 
through  the  fuel  bed  the  nitrogen  is  unchanged,  being  chemically 
inactive,  and  proceeds  into  the  flue  spaces  in  the  same  form  in 
which  it  entered  the  furnace.  The  oxygen,  on  the  contrary, 
enters  into  chemical  reaction,  combining  with  the  carbon  to  form 
CO2  and  CO  and  with  the  hydrogen  to  form  H20.  As  in  all 
chemical  processes,  an  excess  of  the  reagent  must  be  present  in 
order  to  accomplish  a  rapid  and  complete  reaction.  There  will 
always  be  found,  therefore,  in  the  flue  gases  a  very  considerable 
amount  of  excess  or  unused  oxygen.  The  essential  constituents, 
therefore,  to  be  determined  in  the  analysis  of  flue  gases  are : 

1.  C02 

2.  02 

3.  CO 

4.  N2  (by  difference) 

In  the  combustion  of  carbon,  the  reaction  which  occurs  may  be 
represented  by  the  formula  C  +  O2  =  C02.  This  means  that 
for  each  volume  of  oxygen  one  volume  of  CO2  results.  If, 
therefore,  pure  carbon  were  burned  and  the  exact  amount  of  air 
were  supplied  to  completely  represent  the  volumes  indicated  in 
the  above  equation,  the  resulting  flue  gas  would  be  composed  of 
20.78  per  cent  of  C02  and  79.22  per  cent  of  nitrogen.  This, 
therefore,  would  represent  the  extreme  limit  of  theoretical  possi- 
bility as  to  the  percentage  of  the  volume  of  CO2  in  such  a  flue 
gas.  However,  from  the  principle  already  stated  as  to  the  neces- 
sity of  an  excess  of  reagent,  the  rapid  and  complete  oxidation  of 
the  carbon  can  only  be  effected  by  having  an  excess  of  oxygen, 
at  least  50  per  cent  more  than  that  utilized  in  the  combustion, 
and  even  at  this  ratio  the  oxygen  would  begin  to  be  sufficiently 

104 


FLUE  GAS  105 

low  in  amount  to  result  in  the  formation  of  a  very  considerable 
quantity  of  CO.  From  actual  experience  it  would  seem  that  a 
content  of  C02  in  the  flue  gases  of,  say,  12  per  cent  approaches 
the  limit  of  practicability,  while  doubtless  from  8  to  10  per  cent 
of  C02  would  represent  conditions  which  are  above  the  average 
in  practice. 

It  should  be  borne  in  mind  also  that  while  carbon  constitutes 
the  larger  part  of  the  fuel  content,  the  combustion  of  hydrogen 
(which  on  the  average  represents  from  3  to  4  per  cent  of  the 
coal),  would  be  represented  by  the  formula 

2H2  +  O2  =  2H2O 

That  is,  one  volume  of  oxygen  results  in  two  volumes  of  water 
vapor.  Now,  since  in  the  process  of  analysis  the  water  vapor 
condenses  and  does  not  appear  in  the  results,  it  must  follow  that 
the  nitrogen  which  accompanied  the  original  oxygen  into  the 
furnace  in  this  case  is  left  alone  without  an  accompaniment  of 
gaseous  product  corresponding  to  the  CO2  as  in  the  case  of  the 
combustion  of  carbon.  To  this  extent,  therefore,  the  ratio  of 
theoretical  C02  in  the  flue  gases  is  diminished.  From  these 
considerations  it  will  appear  that  the  uses  which  may  be  made  of 
the  constituents  are:  First,  a  very  fair  estimate  of  efficiency  of 
the  firing  may  be  obtained  from  the  percentage  content  of  CO2 
in  the  flue  gases.  If,  for  example,  it  is  known  that  for  the  boiler 
setting  and  equipment  of  a  given  furnace,  it  is  capable  of  carrying 
on  combustion  to  an  extent  which  will  be  represented  by  10  per 
cent  of  C02  in  the  flue  gases,  then  when  the  flue  gases  show 
only  5  per  cent  of  this  constituent,  there  is  evidence  of  careless- 
ness in  firing  which  is  capable  of  correction.  Second,  from  the 
factors  involved  relating  as  they  do  to  the  constituents  of  the  air, 
nitrogen  and  oxygen,  and  also  to  one  constituent  of  the  coal, 
carbon,  and  all  in  the  gaseous  form,  it  is  easy  to  calculate,  by 
means  of  the  common  gas  laws,  the  weight  of  air  used  per  pound 
of  fuel  burned.  This  furnishes  a  ready  method  for  calculating 
other  necessary  data  as,  third,  the  ratio  of  air  entering  the  com- 
bustion zone  to  the  air  actually  entering  into  the  combustion, 
and,  fourth,  the  loss  of  heat  passing  up  the  chimney.  This  factor 
is  most  conveniently  derived  after  having  transferred  the  gas 
volumes  to  weight  as  under  No.  2  above. 


106  FUEL,  GAS,  WATER  AND  LUBRICATION 

Sampling  and  Analysis. — According  to  Professor  White1  "the 
problem  of  obtaining  a  representative  sample  of  a  gas  for  analysis 
presents  in  many  cases  more  difficulties  than  the  analysis  itself ." 
These  difficulties  relate  chiefly  to  leakage  in  the  boiler  setting, 
irregularity  of  flow  in  the  cross-section  of  the  chimney  or  gas  con- 
duit, chemical  reaction  with  the  tube  used  for  sampling,  faulty 
or  leaky  connections,  solubility  of  the  sample  in  water,  etc.  The 
avoidance  or  minimizing  of  these  difficulties  is  a  problem  for 
each  plant.  In  general  the  leakage  in  the  boiler  setting  should 
be  remedied  or  minimized  by  a  liberal  use  of  some  sort  of  luting 
material  on  all  cracks  or  openings  not  intentionally  provided  for 
draft  purposes.  The  point  for  taking  the  sample  should  also 
be  as  near  the  combustion  zone  as  possible.  In  cases  where  it  is 
desired  to  take  samples  within  the  zone  of  combustion,  a  special 
collecting  device  with  a  water-cooled  conduit  to  avoid  chemical 
change  in  the  sample  is  necessary. 

The  difficulty  of  variations  in  the  flow  across  the  area  of  the 
conduit  is  best  met  by  use  of  a  multiple  collecting  device  made 
by  assembling  a  bundle  of  varying  lengths  of  heavy  pyrex  glass 
or  refractory  tubing  in  a  convenient  holder,  and  held  in  place  by 
Portland,  or  still  better  "hytempite"  cement.  Rubber  tubing 
should  be  confined  to  short  connections  only  and  use  made  of 
glass  or  metal  tubing.  None  of  the  water  used  in  aspirating  or 
by  gravity  displacement  in  collecting  the  sample  should  remain 
in  the  holder  in  which  the  gas  is  collected  for  transmission  to  the 
laboratory.  The  analysis  of  the  gas  is  not  essentially  different 
from  that  already  discussed  under  fuel  gases,  except  that  a  smaller 
number  of  processes  are  employed.  The  determinations  ordi- 
narily required  in  a  flue-gas  analysis  are  for  CO2,  02,  CO  and  N2 
by  difference.  The  instrument  most  conveniently  arranged  for 
this  work  is  the  Orsat  apparatus.  It  should  be  assembled  in  the 
simplest  form  and  rugged  in  construction  to  meet  the  conditions 
of  portability.  The  prescriptions  for  use  have  already  been  given 
in  connection  with  the  larger  instrument,  page  95.  Indeed 
that  apparatus  is  simply  an  enlarged  or  extended  Orsat.  It  is 
adapted  to  all  the  uses  intended  for  the  smaller  or  Orsat  appa- 
ratus proper  except  ready  transportation.  In  the  regular  or  small 
Orsat,  carbon  monoxide  is  determined  by  solubility  in  ammoni- 

1  WHITE,  A.  H.,  "Gas  and  Fuel  Analysis,"  pp.  1-13. 


FLUE  GAS 

acal  cuprous  chloride  instead  of  by  fractional  combustion.  The 
larger  apparatus  is  therefore  better  adapted  for  work  with  fuel 
gases,  having  a  high  content  of  CO,  while  the  absorption  method 
as  employed  in  the  small  Orsat  is  well  adapted  for  work  with 
flue  gases. 

Calculation  of  Efficiencies  and  Heat  Losses. — The  flue  gas 
constituents  and  temperatures  afford  a  basis  for  calculating 
efficiencies  and  heat  losses.  Three  general  features  are  usually 
included  as  follows: 

(a)  The  number  of  pounds  of  air  entering  per  pound  of  fuel. 
(6)  The  ratio  of  air  entering  the  grate  to  the  air  used. 
(c)  The  loss  of  heat  passing  up  the  chimney. 

(a)  Pounds  of  Air  Entering  per  Pound  of  Coal. — The  gram 
molecule  of  any  gas,  that  is,  the  molecular  weight  of  the  gas  in 
grams,  has  a  definite  volume  and  is  the  same  for  all  gases; 
namely,  22.4  liters  at  standard  temperature  and  pressure.  For 
example  44  grams  of  C02  has  a  volume  of  22.4  liters;  32  grams 
of  62  has  a  volume  of  22.4  liters,  etc.  In  a  mixture  of  gases, 
therefore,  the  weight  of  each  constituent,  W,  in  22.4  liters  equals 
the  molecular  weight  X  the  percentage  present  thus : 

W  =  molecular  weight  of  component  X  per  cent         (1) 

In  arriving  at  the  weight  of  air  entering  the  grate,  the  weight 
of  the  total  nitrogen  will  give  the  most  direct  factor  for  calculating 
the  air.     For  example,  making  use  of  equation  (1)  the  weight  of 
nitrogen,  W1,  in  a  gram-molecule-volume  would  be : 
W1  =  28  X  per  cent.  N2 

In  order  to  refer  the  weight  of  nitrogen  present  to  a  unit  quan- 
tity of  fuel,  we  shall  need  to  determine,  first  the  amount  of  pure 
carbon  involved  in  the  production  of  the  unit  volume  of  flue  gas. 
This  can  be  readily  accomplished  by  deriving  the  weight  of 
carbon  in  the  gas  and  making  one  gram  of  carbon  the  unit  of 
reference.  For  example,  £}  of  the  C02  and  -|f  of  the  CO  present 
is  carbon. 

If  we  let  C  represent  the  weight  of  carbon  in  the  unit  volume, 
then 

C  =  i?  x  44CO2  +  ^  X  28CO 

hence 

CO  =  12(C20+CO) 


108  FUEL,  GAS,  WATER  AND  LUBRICATION 

If,  therefore,  C  represents  the  number  of  grams  of  carbon 
which  deliver  a  flue  gas  with  Wl  grams  of  nitrogen,  then  the 

Wl 
weight  of  nitrogen  per  gram  of  carbon  burned  is  ^r  or  in  terms 

of  the  assigned  values, 

28N>  1NZ 

12(CO2  +  CO)       3(C02  +  CO) 

Assuming  for  illustration  a  chimney  gas  of  the  following  compo- 
sition : 

PER  CENT 

C02 10.0 

02 8.0 

CO 0.5 

N2 81.5 

resulting  from  the  combustion  of  a  coal  having  70  per  cent  of 
carbon  exclusive  of  the  carbon  lost  in  the  ash.  Then  by  sub- 
stituting these  values  in  equation  (2)  we  have : 

TTTI  '     />    ol.O  10-1-1  TVT 

=  3(10  +  0.5)  ""*•"  Pa™*' 

That  is,  18.11  grams  nitrogen  in  the  flue  gases  accompany  the 
combustion  of  1  gram  of  carbon.  Similarly  there  would  be  18.11 
Ib.  of  nitrogen  in  the  flue  gases  from  1  Ib.  of  carbon,  and  for  a  coal 
of  70  per  cent  carbon  the  weight  would  be  0.70  X  18.11  =  12.68 
Ib.  N2.  Since  nitrogen  passes  through  the  furnace  unchanged  the 
calculation  to  the  equivalent  weight  of  air  entering  is: 

77  :100  ::  12.68  :  x 

x  =  16.47 
Hence  the  weight  of  air  entering  per  pound  of  coal  is  16.47  Ib. 

(b)  Ratio  of  Air  Entering  to  Air  Used. — From  the  discussion 
under  (a)  the  weight  of  oxygen  per  pound  of  carbon  would  be 
represented  by  the  expression, 

3202  802  (  } 

~  12(CO2  +  CO)      3(C02  +  CO) 
Substituting  the  values  indicated  under  (a)  we  have 

wi  -        8X8      .   _  o  no 

~  3(10  +  0.5)   " 
and  for  a  coal  having  70  per  cent  of  carbon  the  weight  would 


FLUE  GAS  109 

be  1.42  Ib.  per  pound  of  coal.  Calculating  the  oxygen  to  the 
equivalent  of  air, 

23  :100  ::1.42  :x 
x  =  6.17 

Hence,  the  weight  of  air  passing  through  unused  is  6.17  Ib.  per 
pound  of  coal. 

From  (a)  and  (b)  therefore 

POUNDS 

Total  air  entering 16.47 

Air  unused 6.17 

Air  used 10.30 

^^r  =  1.60     Ratio  of  air  entering  to  air  used. 

(c)  The  Loss  of  Heat  Passing  Up  the  Chimney. — The  factors 
which  enter  into  the  calculation  of  heat  losses  in  chimney  gases 
are  (1)  the  weight  of  the  flue  gas  per  pound  of  fuel,  (2)  the  specific 
heat  in  B.t.u.  per  pound,  and  (3)  the  rise  in  temperature  or 
difference  in  temperatures  (t  —  Z1)  between  the  entering  air 
and  the  gases  as  they  leave  the  furnace. 

1.  The  weight  of  the  gas  per  pound  of  fuel  may  be  readily 
derived  from  the  formula  for  W  as  developed  under  (a)  and  (b) 
above.  Letting  Wv  represent  the  weight  of  the  mixed 'gases  per 
pound  of  pure  carbon,  then  by  a  similar  procedure  to  that  shown 
in  equation  (2)  under  (a)  and  equation  (3)  under  (&)  we  would 
have  for  the  total  weight  of  all  of  the  components  per  pound  of 
carbon : 

11C02  +  8Q2  +  7CO  +  7N2 
3(CO2  +  CO) 

Or,  since  CO  +  N2  =  100  —  CO2  —  O2  this  expression  may  be 
still  further  simplified  to  read : 

w    _  4CO2  +  O2  +  700  ,„ 

3(C02  +  CO) 

Assuming  the  coal  used  as  in  (a)  and  (b)  to  have  70  per  cent  of 
carbon  (the  carbon  of  the  ash  having  been  subtracted),  then 
by  substituting  the  percentage  values  for  the  chimney  gas  as 


110  FUEL,  GAS,  WATER  AND  LUBRICATION 

already  indicated  and  multiplying  by  0.70  we  would  have  the 
weight  of  gases  per  pound  of  fuel  : 

_  4  X  10  +  8  +  700  _ 

3(10  +  0.5) 
Therefore  for  (1) 

W  =  16.62  Ib.  dry  gases  per  pound  of  fuel. 
2.  The   specific   heats   of   the   various   components,  at  con- 
stant pressure  in  B.t.u.  per  pound,  calculated  for  the  interval 
60°F.-600°F., 

C02  =  0.222 
O2  =  0.217 
CO  =  0.245 
N2  =  0.2407 
H2O  =  0.4673 

From  which  it  appears  that  an  average  specific  heat  of  0.24  for 
all  the  constituents  exclusive  of  water  vapor  may  properly  be 
applied.     Assuming,  therefore,  the  (t  —  t1)  values  of  60°  entering 
and  600°  leaving,  we  have  a  total  loss  L  for  the  dry  gases  thus  : 
L  =  16.62  X  0.24  X  540 
L  =  2,154  B.t.u. 

Assuming  a  heat  value  of  12,000  B.t.u.  for  the  coal  per  pound  as 
fired,  then  the  percentage  loss,  L1,  would  be, 

_  2,154 

~> 


L1  =  17.95  per  cent. 

Other  Losses.  —  In  obtaining  a  heat  balance  as  in  boiler  tests, 
other  heat  losses  are  taken  account  of.     They  include: 

(A)  The  latent  heat  of  vaporization  of  moisture. 

(B)  The  heat  of  the  water  vapor  passing  off  at  the  tempera- 

ture of  the  chimney. 

(C)  The  heat  combustion  of  carbon  to  CO,  instead  of  to  CO2. 

(D)  The  unburned  carbon  in  the  ash. 

(A)  The  water  from  which  the  loss  of  heat  is  calculated  is  made 
up  of: 

(a)  The  total  hydrogen  of  the  coal  burning  to  H20, 

that  is  H  X  9. 

(6)  The  free  moisture  of  the  coal. 
(c)  The  moisture  of  the  air  as  indicated  by  the  relative 
humidity. 


FLUE  GAS  111 

The  sum  of  the  three  amounts  of  water  referred  to  the  unit  of 
1  Ib.  of  coal  multiplied  by  the  factor  for  the  latent  heat  of  vapori- 
zation represents  the  heat  loss  in  B.t.u.  per  pound  of  coal  thus: 

B.t.u.  loss 


per  pound 
of  coal 


=  Weight  of  H20  X  966 


(B)  Having  found  the  weight  of  water  as  under  (A)  the  heat 
loss  due  to  rise  in  temperature  from  room  temperature,  t,  to  212°, 
and  from  212°  to  temperature  of  flue  gases,  T,  is  found,  using  the 
specific  heat  factor  for  the  water  vapor,  of  0.467,  thus : 

B.t.u.  loss 


per  pound 
of  coal 


H20  X  (212  -  0  +  H20  X  0.467  X  (T  -  212) 


(C)  The  heat  loss  due  to  the  burning  of  carbon  to  CO  instead 
of  CO  2  is  found  by  multiplying  the  weight  of  carbon  thus  entering 
into  the  reaction  per  pound  of  coal,  by  the  difference  between 
the  calorific  value  of  carbon  burned  to  CO2  and  carbon  burned  to 
CO,  thus: 


B.t.u.  loss  from  CO 
per  pound 
of  coal 


Weight  C  in  CO  X  10,150 


(D)  The  loss  of  heat  due  to  combustible  matter  passing 
through  with  the  ash  unburned  is  found  by  determining  the 
combustible  in  the  ash  as  carbon,  c,  and  referring  it  to  the  total 
refuse,  r,  in  its  proper  proportion,  x,  to  the  ash,  a,  of  the  original 
fuel  thus: 

c  :  r  ::  x  :  a 

Having  the  value,  x,  in  percentage  of  the  original  coal  as  fired, 
then : 

Heat  loss  per  pound  1   = 

of  coal  from  unburned  carbon  J 

In  the  use  of  the  factor  14,550,  it  is  assumed  that  the  residual 
combustible  in  the  ash  is  carbon  only,  with  a  heat  value  as 
indicated. 


CHAPTER  XVII 
BOILER  WATERS 

THEIR  EXAMINATION,  CHARACTER  AND  TREATMENT 

Water  Analysis. — Waters  are  examined  for  two  very  different 
purposes.  First,  the  object  may  be  to  determine  the  potability 
or  sanitary  character  of  the  water;  and,  second,  it  may  be  desired 
to  learn  the  behavior  or  value  of  the  water  for  industrial  uses. 
The  requirements  under  each  division  are  very  different.  In 
order  to  be  sanitary,  a  water  must  be  free  from  certain  forms  of 
organic  matter  which  might  indicate  possible  contamination  with 
sewage  or  furnish  a  suitable  breeding  medium  for  disease  germs. 
Within  reasonable  limits,  the  amount  of  mineral  constituent  is  of 
little  importance.  On  the  contrary,  however,  the  value  of  a 
water  for  industrial  purposes  depends  very  largely  on  the  kind 
and  amount  of  the  dissolved  mineral  substance,  while,  as  a  rule, 
little  importance  is  attached  to  the  organic  material  present. 
This  is  especially  true  in  the  case  of  those  waters  which  are  to  be 
used  for  boiler  purposes,  and  it  is  this  phase  of  the  subject  which 
is  of  immediate  interest. 

Source  of  the  Mineral  Constituents. — Natural  waters  in 
passing  through  the  soil  come  in  contact  with  certain  products 
of  decomposition  and  decay.  Some  of  these  substances,  notably 
carbon  dioxide,  humic  acid,  etc.,  are  taken  up  by  the  waters,  in 
which  condition  their  power  to  dissolve  mineral  matter  is  greatly 
increased.  In  this  way  the  decomposition  of  feldspar,  limestone, 
etc.,  is  constantly  going  on,  the  result  to  the  percolated  water 
being  that  there  is  taken  into  solution  varying  quantities  of 
silica,  salts  of  iron,  aluminum,  magnesium,  sodium,  potassium, 
etc.  As  a  rule,  therefore,  the  less  contact  natural  waters  have 
had  with  the  soil,  or  the  more  insoluble  the  earthy  matter  with 
which  they  have  come  in  contact,  the  smaller  will  be  the  amount 
of  mineral  constituents  dissolved:  and,  conversely,  the  deeper  the 

112 


BOILER  WATERS  113 

source  of  supply,  the  greater  the  opportunity  for  dissolving  such 
material,  and  consequently  the  greater  will  be  the  amount  of  such 
substances  in  solution.  For  this  reason  it  has  been  sometimes 
customary  to  divide  waters  into  three  classes: 

1.  Surface  water, 

2.  Shallow  wells  and  spring  waters, 

3.  Deep  wells  and  artesian  waters. 

Surface  waters  are  such  as  are  found  in  lakes,  streams,  and 
artificial  ponds,  and  with  these  might  also  be  considered  cistern 
or  rain  waters;  shallow  well  waters  may  be  considered  as  those 
obtained  from  wells  or  borings  which  extend  into  the  drift  not 
to  exceed  30  or  40  ft.;  while  deep-well  waters  may  be  considered 
those  that  are  obtained  from  a  depth  of  over  100  ft.  These 
divisions  are  not  sharply  drawn,  and,  indeed,  the  classes  merge 
into  each  other.  This  is  more  readily  seen  from  the  fact  that 
many  streams,  for  a  large  part  of  the  year  at  least,  are  fed  by 
waters  which  have  their  source  in  tile  drains  and  springs.  The 
system  of  underground  drainage  so  largely  carried  on  in  these 
days,  therefore,  gives  to  the  waters  of  smaller  streams  at  least 
many  of  the  characteristics  of  the  water  from  the  shallow  wells. 
This  feature  is  more  pronounced  during  the  dry  months  of  the 
year,  as,  for  example,  in  the  late  summer  and  fall.  The  amount 
of  mineral  matter,  therefore,  varies  inversely  as  the  volume  of 
water  in  these  minor  streams.  On  the  other  hand,  large  bodies 
of  water  and  larger  streams,  especially  those  in  districts  where 
they  come  in  contact  with  the  more  insoluble  formations,  are 
remarkably  free  from  mineral  matter.  This  is  especially  notice- 
able in  the  waters  of  Lake  Superior,  and  in  many  of  the  rivers  of 
the  north-central  region  of  the  United  States.  In  certain  regions, 
also,  as  in  the  delta  of  the  Mississippi,  water-bearing  sands  are 
sometimes  found  at  very  considerable  depths,  but  with  extremely 
small  amounts  of  mineral  matter  present.  * 

It  will  be  seen  from  the  above  discussion  that  any  classification 
based  merely  upon  the  source  of  a  water  will  have  little  practical 
value.  Before  attempting  any  classification,  however,  based 
upon  the  character  of  the  dissolved  mineral  constituents  it  will 
be  necessary  to  review  the  processes  by  which  these  substances 
become  a  part  of  the  water,  and  to  note  their  properties  and 
behavior  under  the  conditions  of  actual  use  in  steam  boilers. 


114  FUEL,  GAS,  WATER  AND  LUBRICATION 

Chemical  Characteristics  of  the  Mineral  Constituents. — Cal- 
cium carbonate,  CaCOg,  and  magnesium  carbonate,  MgC03,  are 
the  chief  constituents  of  lime  rock.  Finely  divided  particles  of 
these  substances  exist  throughout  all  the  clayey  deposits  of  the 
drift  region.  The  percolating  water  holding  carbon  dioxide, 
C02,  in  solution  has  the  property  of  a  weak  acid,  H20  +  C02  = 
H2CC>3,  and  in  this  form  is  a  solvent  for  the  above  substances, 
forming  bicarbonates,  thus : 

CaC03  +  H2C03  =  CaH2(C03)2 
MgC03  +  H2C03  =  MgH2(C03)2 

These  dissolved  bicarbonates  are  readily  broken  down  by  heat, 
thus: 

CaH2(C03)2  =  CaC03  +  H20  +  C02 

The  water  alone  with  the  carbon  dioxide  gas  driven  out  of  it  is  not 
a  solvent  for  calcium  carbonate,  and  the  latter  is  precipitated. 

Feldspars  of  various  sorts  are  usually  distributed  throughout 
the  drift  deposits.  These  also  are  slowly  decomposed  by  car- 
bonated waters  thereby  adding  to  the  water,  compounds  of 
sodium,  potassium,  iron  and  aluminum,  as  well  as  hydrated 
silica,  which  is  also  soluble.  The  general  type  of  this  reaction 
may  be  shown,  thus: 

Al203.K20.6Si02  +  2H2C03  =  Al203.2Si02.2H2O  +  K2CO3 + 4Si02 

Feldspar  Kaolin 

In  this  way  complex  or  impure  rocks  may,  upon  their  decompo- 
sition, yield  small  quantities  not  only  of  lime  and  magnesium 
in  solution  as  bicarbonates,  but  also  iron  in  a  bicarbonate  form, 
as  well  as  salts  of  sodium,  potassium,  and  silicic  acid.  This 
result  would  be  more  readily  understood  if  we  were  to  enter  into 
a  study  of  the  composition  of  the  drift,  especially  of  a  region  like 
the  Mississippi  Valley  where  the  glacial  clay  has  a  very  consider- 
able admixture  of  ground  rock  such  as  feldspar,  hornblende,  mica, 
dolomite,  etc.  Moreover,  since  all  drift  formation  has  been  de- 
posited in  contact  with  or  by  means  of  sea  water,  we  expect  a 
greater  or  less  amount  of  mineral  substances  to  be  present  due 
to  such  water;  namely,  sodium  chloride,  calcium  sulphate,  etc. 

Solubility  of  Gypsum. — We  are  familiar  with  the  solubility  of 
sodium  chloride,  but  calcium  sulphate  or  gypsum  is  also  soluble, 


BOILER  WATERS  115 

although  to  a  less  degree,  and  this  without  the  aid  of  carbon 
dioxide.  Its  solubility,  for  example,  may  be  illustrated  by  the 
following  table : 

TABLE  XV. — SOLUBILITY  OF  GYPSUM 

(CaS04  +  2H20) 

1  part  dissolves  in  about      500  parts  of  water  at  ordinary  temperature 
1  part  dissolves  in  about  1,200  parts  of  water  at  250°F. 
1  part  dissolves  in  about  1 , 800  parts  of  water  at  SOOT. 
1  part  dissolves  in  about  3 , 800  parts  of  water  at  325°F. 

From  the  above  facts  it  may  be  readily  understood  how  the 
mineral  constituents  come  to  be  dissolved  in  all  underground 
waters.  The  kind,  amount,  and  properties  of  these  substances 
indicate  directly  the  behavior  of  a  water  when  used  for  boiler 
purposes.  Almost  without  exception  their  presence  is  objec- 
tionable for  reasons  which  will  be  evident  from  the  following 
discussion. 

Effects  of  Impurities. — The  difficulties  which  attend  the  use  of 
water  in  the  generation  of  steam  are  three  in  number : 

First,  mineral  scale  is  formed  upon  the  shell,  flues,  and  sheets; 
second,  foaming  or  priming  may  occur;  and,  third,  the  water  may 
have  corrosive  action  and  weaken  the  metal  of  which  the  boiler  is 
composed. 

The  constituents  of  a  water,  therefore,  naturally  group  them- 
selves under  these  three  heads: 

1.  Scaling  ingredients. 

2.  Foaming  ingredients. 

3.  Corrosive  ingredients. 

Scaling  Ingredients. — Scaling  ingredients  are  always  con- 
sidered as  including  silica  and  any  combination  of  iron,  alumi- 
num, calcium,  and  magnesium.  Since  the  formation  of  scale  is 
the  most  common  and  perhaps  the  most  evident  difficulty  which 
accompanies  the  use  of  a  boiler,  it  has  sometimes  been  made  the 
basis  of  a  classification  for  waters.  At  a  meeting  of  the  American 
Association  of  Railway  Chemists  at  Buffalo,  N.  Y.,  May  24,  1887, 
a  schedule  of  classification  was  adopted.  Waters  containing 
varying  quantities  of  scaling  material  per  U.  S.  gallon  were 
graded  as  in  the  table  below: 


116  FUEL,  GAS,  WATER  AND  LUBRICATION 

TABLE  XVI. — CLASSIFICATION  OF  WATERS  BY  THE  ASSOCIATION  OF  RAILWAY 

CHEMISTS 

Below  8  grains Very  good 

8  to  15  grains Good 

15  to  20  grains Fair 

20  to  30  grains Poor 

30  to  40  grains Bad 

Over  40  grains Very  bad 

In  this  table  the  first  line  was  added  by  the  Chicago,  Burlington 
&  Quincy  Railway  to  fit  the  case  of  Lake  Michigan  water,  which 
has  approximately  8  grains  or  less  per  gallon. 

This  classification  is  relative  only,  since  a  wider  study  of  the 
subject  has  indicated  the  necessity  of  taking  into  account  the 
kind  of  scale  which  would  form  and  the  other  ingredients  in  addi- 
tion to  those  which  produce  scale.  The  scale  when  formed,  may 
be  dense  and  flint-like  or  open  and  porous.  These  characteristics 
result  from  the  various  types  of  mineral  content  involved.  In 
general,  a  hard,  flinty  scale  is  due  to  the  presence  of  calcium  or 
magnesium  sulfates;  while,  in  waters  in  which  only  the  carbon- 
ates of  these  substances  are  present,  the  scale  will  be  more 
open  and  friable.  Indeed,  a  very  large  number  of  waters  are 
met  with  where  only  carbonate  hardness  is  present.  In  these 
cases  the  major  part  of  the  incrusting  solids  appears  as  mud  or 
sludge.  For  these  and  other  reasons  the  above  classification 
has  not  met  the  needs  of  the  case  and  has,  indeed,  not  been 
adopted  to  any  considerable  extent.  A  much  more  practical 
classification  would  take  account  of  all  of  the  various  constituents 
and  the  characteristics  for  which  they  are  responsible.  The 
method  of  classification  devised  by  the  Chicago,  Burlington  & 
Quincy  Railroad  is  based  on  the  amount  of  these  various  con- 
stituents. Since  the  full  meaning  of  the  same  can  be  better 
understood  later,  it  is  reproduced  at  the  end  of  this  chapter. 

Effect  of  Scale. — Boiler  scale  is  a  disadvantage  for  the  reason 
that:  First,  it  retards  the  transmission  of  heat;  second,  it  pro- 
motes the  formation  of  a  high  temperature  in  the  plates,  with  a 
possibility  of  softening  the  same;  third,  the  sudden  rupture  or 
opening  up  of  the  scale  may  admit  water  to  the  highly  heated 
metal,  forming  hydrogen  and  oxygen ;  fourth,  the  higher  tempera- 
ture of  the  steel  thus  maintained,  even  though  not  reaching 


BOILER  WATERS  117 

the  danger  point,  promotes  the  absorption  of  sulphur  and  oxygen 
and  thus  causes  a  deterioration  of  the  metal.  Doubtless  the 
chief  item  in  this  list,  by  reason  of  its  continuous  and  total  aggre- 
gate effect,  is  the  decrease  of  heat  conductivity,  requiring  a  larger 
amount  of  fuel.  Authorities  differ  as  to  the  extent  of  loss.  A 
conservative  estimate  would  place  the  loss  of  fuel  at  10  per  cent 
for  each  iV  in.  in  thickness  of  the  scale.  The  difficulties  attend- 
ing the  estimation  of  the  fuel  loss  are  great,  and  it  is  to  be 
expected  that  a  rather  wide  range  of  results  is  found  in  the 
published  data.1 

A  test  of  the  steaming  efficiency,  made  upon  an  Illinois  Central 
locomotive  by  the  University  of  Illinois  in  1898  and  described  in 
the  Railway  Gazette  for  the  following  year,  indicated  a  loss  of 
heat,  with  a  scale  averaging  -fa  in.  in  thickness,  amounting  to 
9.6  per  cent.  The  same  engine  was  tested  before  overhauling  at 
the  shops  and  was  returned  after  cleaning  for  the  comparative 
test.  An  interesting  computation  was  made  on  the  same  road 
at  a  much  earlier  date,  in  which  the  performance  sheets  for  120 
locomotives  were  taken  with  reference  to  the  consumption  of  coal 
before  overhauling,  and  these  results  were  compared  with  the  coal 
consumed  for  the  3  months  immediately  following  such  a  cleaning, 
with  an  average  for  the  120  engines  of  almost  exactly  10  per  cent 
in  favor  of  the  scale-free  condition.  Many  other  tests  have  sub- 
sequently been  made  more  or  less  confirmatory  of  these  results. 

Foaming  Ingredients. — The  non-scaling  or  foaming  ingredients 
are  considered  to  be  the  salts  of  the  alkalies,  such  as  sodium 
chloride,  sodium  sulphate,  sodium  carbonate,  potassium  chloride, 
potassium  sulphate,  potassium  carbonate,  etc.  Other  conditions 
contribute  to  the  tendency  of  water  to  foam,  such  as  the  presence 
of  organic  matter,  especially  such  substances  as  may  form  soap. 
The  presence  of  finely  divided  solids  in  suspension  is  also  a  con- 
tributing cause. 

1  BRECKENRIDGE,  L.  P.,  The  effect  of  scale  on  the  evaporation  of  a  loco- 
motive boiler :  R.  R.  Gazette,  vol.  31,  new  series,  p.  60,  1899. 

Am.  Ry.  Eng.  Assn.,  1914,  p.  692:  " it  is  concluded  that  the 

saving  of  $977  per  locomotive  represents  7  cents  per  pound  of  excess  scaling 
matter  entering  the  boiler " 

Univ.  of  111.,  Eng.  Exp.  Sta.,  Bull  11. 

Am.  Ry.  Eng.  and  Maint.  of  Way  Assn.,  p.  41,  etc.,  Jan.  1907. 


118  FUEL,  GAS,  WATER  AND  LUBRICATION 

The  objections  against  foaming  may  be  stated  as  follows: 
First,  the  rising  of  the  water  in  the  gage  glass  or  blowoff  cocks 
makes  it  difficult,  if  not  impossible,  to  know  the  height  of  the 
water  in  the  boiler;  second,  the  discharge  of  wet  steam  or  of 
steam  carrying  a  considerable  quantity  of  water  is  exceedingly 
wasteful  of  heat  and  makes  it  difficult  to  keep  up  the  steam  pres- 
sure; third,  there  is  danger  of  large  quantities  of  water  getting 
into  the  cylinders  where,  by  reason  of  its  incompressibility  and 
inability  to  pass  quickly  out  of  the  ports,  a  cylinder  head  may 
thereby  be  blown  off;  and,  fourth,  the  grit  carried  along  with 
the  water  promotes  the  cutting  of  the  walls  of  the  cylinders  and 
valve  seats,  thus  making  a  re-boring  of  the  cylinders  necessary. 

Concerning  the  causes  which  promote  foaming,  they  are  not  so 
easy  to  define  or  classify  as  in  the  case  of  scaling,  and  they  do  not 
always  relate  directly  to  the  character  of  the  dissolved  mineral 
substance.  The  tendency  to  foam  varies  greatly,  for  example, 
with  the  two  general  types  of  boilers  employed,  those  used  for 
stationary  purposes,  and  the  locomotive  type.  It  might  be 
said,  indeed,  that  to  the  above  mentioned  conditions  of  the  water 
might  be  added  the  nature  of  the  spaces  in  which  the  generation 
of  steam  takes  place.  A  network  of  staybolts  and  braces  in  a 
steaming  space  of  small  volume  at  best  will  be  more  conducive 
to  foaming  than  the  opposite  conditions.  The  structure  and 
steaming  capacity  of  the  locomotive,  therefore,  greatly  increase 
the  tendency  of  this  type  of  boiler  to  foam.  Tests  on  numerous 
railroads  pretty  generally  agree  upon  the  following  facts  concern- 
ing the  foaming  in  locomotives.  When  a  density  of  the  water 
due  to  the  presence  of  alkali  sulphate  or  chloride  reaches  approxi- 
mately 100  grains  to  the  gallon,  foaming  is  apt  to  occur,  especially 
when  the  engine  is  put  under  heavy  work.  This  means  that  in 
the  raw  water,  before  condensation  has  been  carried  on,  a  content 
of  25  grains  per  gallon  would  reach  the  foaming  stage  when  three 
or  four  tankfuls  had  been  taken  into  the  boiler.  However,  a 
wide  variation  is  due  to  the  type  of  foaming  ingredients,  since  a 
less  amount  of  alkali  salt  will  cause  foaming  where  part  of  the 
substance  is  alkali  carbonate,  Na2CO3,  or  soda  ash.  Where 
much  organic  matter  also  is  present,  a  still  less  amount  of  free 
alkali  will  cause  foaming.  Indeed,  cases  have  been  met  with 
where  15  to  25  grains  per  gallon  of  alkali  salts  have  produced 


BOILER  WATERS  119 

foaming,  when  one-half,  for  example,  of  such  salts  were  in  the 
form  of  alkali  carbonates,  accompanied  by  a  very  considerable 
amount  of  organic  matter.  Foaming  in  stationary  boilers 
would  scarcely  be  caused  by  double  the  amount  mentioned 
above. 

Corrosive  Ingredients. — Much  disagreement  exists  regarding 
the  causes  of  corrosion.  Certain  conditions  will  produce  galvanic 
action  between  different  metals  used  in  construction,  or  even 
between  different  parts  though  made  of  the  same  metal,  and 
this  action  eats  away  the  metallic  surfaces.  Flaws,  cinder  scales, 
oxide  nodules,  etc.,  will,  probably  for  a  similar  reason,  produce 
pitting.  Along  sharp  angles  of  construction,  where  the  metal 
has  been  put  under  strain,  corrosion  will  frequently  occur.  Car- 
bonic acid  gas  or  oxygen,  when  dissolved  in  water,  are  solvents  for 
iron.  Of  course,  the  heat  soon  drives  these  -gases  out  of  the 
water,  but  corrosion  in  the  vicinity  of  the  feed  inlet  may  be  due 
to  this  cause.  Some  waters  percolate  through  culm  heaps  or 
coal  mine  refuse  or  drainage  and  have  produced  in  them  free 
sulphuric  acid  from  the  oxidation  of  iron  pyrites,  or  they  may 
take  up  sulphate  of  iron  or  aluminium,  all  of  which  chemicals 
render  a  water  positively  and  vigorously  corroding. 

Nitrates  are  seldom  encountered,  but,  when  present  in  any 
considerable  amount,  are  strongly  corroding.  Calcium  and 
magnesium  chlorides  are  also  strongly  corroding.  But,  after  all, 
it  may  be  noted  that  many  conditions  can  exist  to  neutralize 
the  corrosiveness  of  a  water.  For  instance,  there  may  be  formed 
a  hard,  dense  scale  which  will  effectually  protect  the  iron.  In 
this  case,  however,  we  would  expect  to  see  some  tendency  toward 
corrosion  and  pitting  under  the  scale. 

If,  now,  we  attempt  to  classify  waters  according  to  the  mineral 
constituents  above  outlined,  we  would  have: 

Classification.  Class  I. — This  class  includes  such  waters  as 
have  present  free  sodium  carbonate  or  more  than  enough  sodium 
to  unite  with  the  sulphate,  chloride,  and  nitrate  radicals  or  ions. 
There  would  be  left,  therefore,  only  carbon  dioxide,  CO2,  to  unite 
with  the  remaining  sodium  and  also  the  calcium,  magnesium,  and 
iron.  Such  waters  have  only  temporary  hardness,  there  being  no 
sulphates  of  calcium  or  magnesium.  Upon  boiling  or  using  in  the 
steam  boiler,  only  a  sludge  forms  instead  of  scale.  The  car- 


120  FUEL,  GAS,  WATER  AND  LUBRICATION 

bonates  are  all  in  the  bicarbonate  form  and,  hence,  are  stable  in 
the  cold,  but  decompose  upon  heating.  Waters  of  this  class  are 
very  widely  distributed  throughout  the  drift  region,  and  the 
source  is  usually  from  deep  wells. 

Class  II.— The  waters  of  this  class  contain  calcium  or  magne- 
sium sulphate  as  well  as  bicarbonates,  but  not  the  chlorides  of 
these  elements.  They  have,  therefore,  permanent  hardness  and 
form  a  hard,  flinty  scale.  Such  waters  are  usual  in  surface 
supplies  and  in  most  shallow  wells. 

Class  III. — This  includes  such  waters  as  contain  corroding 
salts  or  free  acid  in  solution,  such  as  the  chlorides  or  nitrates  of 
magnesium  or  calcium,  the  sulphate  of  iron  or  free  sulphuric  acid. 
Such  waters  are  infrequent  but,  because  of  their  corroding  charac- 
ter, should  be  recognized  when  met  with. 

The  Chemical  Treatment  of  Boiler  Waters. — From  what  has 
preceded  it  will  be  readily  understood  that  the  treatment  of 
boiler  waters  must  follow  closely  along  the  line  of  the  chemical 
character  of  dissolved  ingredients,  with  a  view  also  to  the  proper- 
ties which  various  ingredients  impart  to  the  water.  In  the 
first  instance,  it  must  be  remembered  that  all  natural  water  is 
strongly  impregnated  with  carbon  dioxide.  We  should  recall 
again  the  fact  that  the  presence  of  this  gas  in  the  water  has 
furnished  a  solvent  condition  which  has  resulted  in  the  formation 
of  bicarbonates,  especially  of  lime,  magnesium,  and  iron. 

In  1766,  Cavendish  announced  the  discovery  that  lime  water 
added  to  certain  hard  waters  would  soften  them,  but  the  prac- 
tical application  of  the  principle  was  not  made  until  1841  when  Dr. 
Thomas  Clark,  of  Aberdeen,  Scotland,  obtained  patents  covering 
both  the  process  and  the  apparatus  employed.  Clark's  process 
has  now  mainly  historic  interest.  It  was  ineffective  on  waters 
with  sulphate  or  permanent  hardness.  While  his  methods  seem 
crude  in  comparison  with  present-day  processes,  certain  features 
have  attained  a  permanent  place  in  boiler- water  literature. 
One  is  the  use  of  lime  and  another  is  the  use  of  a  standard  soap 
solution  for  measuring  the  total  hardness  in  degrees,  each 
degree  representing  one  grain  per  Imperial  gallon  of  soap-destroy- 
ing material.  This  is  known  as  Clark's  scale  of  hardness. 
Numerous  other  methods  are  in  vogue  for  indicating  hardness  of 
water.  The  table  under  "  Standards  for  indicating  degrees  of 


BOILER  WATERS 


121 


hardness,"  page  132,  will  be  helpful  in  showing  their  relative 
values. 

It  is  at  once  evident  that  there  are  two  general  types — Class  I 
and  Class  II  as  referred  to  above  under  "  Classification "  which 
have  material  in  solution  of  two  different  characteristics  requir- 
ing two  different  processes  when  softening  methods  are  involved. 

Because  of  the  fact  that  the  compounds  of  the  first  group  of 
substances  are  easily  decomposed  by  heat  and  thus  discharged 
from  solution,  we  have  a  subdivision  of  scaling  ingredients  into: 

I.  Those   which   are   designated   as   constituting   temporary 
hardness,  and 

II.  Those  which  constitute  permanent  hardness  of  water. 
The  first  division  is  present  in  all  waters  and  includes  the 

larger  part  of  the  scaling  matter;  the  latter  is  variable  in  amount 
and  frequently  absent,  so  far  as  the  scaling-  constituents  are 
concerned.  These  two  general  divisions  or  types  of  scaling 
material  must  be  borne  in  mind,  because  they  form  the  basis  of 
all  practical  methods  for  water  treatment,  indeed,  each  division 
represents  a  process  or  a  method  which  must  be  followed  for 
the  removal  of  these  substances.  This  may  be  more  clearly 
illustrated  by  the  following  outline: 

TABLE  XVII. — SCALING  MATTER  AND  TREATMENT 


"Excess"  CO2 

For  this 

CaCOs  +  2H2O 

Division  I. 

division  use 

Scaling 

Bicarb  onates 

CaH2(CO3)2      • 

Ca(OH)2.    • 

CaCOs  +  CaCOs  +  2H2O 

matter 

as: 

MgH2  (CO3)2 

The.  results 

Mg(OH)2  +  CaCOs  +  2H2O 

is     prin- 

FeH2 (COs)2 

are 

FeCOs1  +  CaCOs  +  2H2O 

cipally 

For  this 

com- 
posed of 

Division  II. 
Sulphates  as: 

MgS04 
CaS04 

division  use 
Na2CO3.     • 

MgCOs  +  Na2SO4 
CaCOs    +  Na2SO4 

, 

FeSO4 

The  results 

FeCOs1  +  Na2SO4 

are 

It  will  be  readily  seen  from  this  outline  that  the  first  division, 
carrying  the  bicarbonates,  may  be  removed  from  the  water  either 
by  heat  or  by  the  addition  of  some  chemical  which  will  absorb 
the  " excess"  and  "bicarbonate"  carbon  dioxide.  If  we  were  to 
depend  upon  heat  for  this  work,  it  would  be  a  long  process  for 
the  reason  that  ordinarily  these  bicarbonates  are  not  completely 

substance  quickly  breaks  down  into  Fe  (OH) 3  thus: 
2FeCO3  +  3H2O  +  O  =  2Fe(OH)3  +  2CO2 


122  FUEL,  GAS,  WATER  AND  LUBRICATION 

broken  down  except  upon  rather  prolonged  boiling,  say  for  15  or 
20  min.  or  even  \  hr.,  and  this  again  would  indicate  the  impracti- 
cability of  such  a  method,  because  of  the  expense  involved. 

Treatment  with  Lime,  Ca(OH)2. — Since  hydrated  lime  reacts 
at  ordinary  temperatures  and,  moreover,  is  the  least  expensive 
of  the  possible  reagents,  it  is  made  use  of  to  react  with  the  C02 
of  Division  I  of  Table  XVIII. 

In  measuring  the  amount  of  Ca(OH)2  needed  for  treating  a 
water,  it  must  be  borne  in  mind  that  the  C02  dissolved  as  H2C03 
will  react  with  the  Ca(OH)2  the  same  as  the  bicarbonates. 
Hence,  we  have  a  series  of  reaction  thus : 


(a)        H2CO 


f  CaH2(CO3)2 
(6)      {  MgH2(C03)2 
FeH2(C03)2 


CaC03  +  2H20 


Ca(OH)2  =  \  CaCO3  +  CaCO3 

Mg(OH)2  +  CaCOs 
FeCO3  +  CaCO3 


The  total  C02  to  be  thus  taken  care  of  is  designated  as  (a) 
"  excess"  or  "free"  carbon  dioxide,  and  (6)  "  half  -bound"  or 
one-half  of  the  "  bicarbonate "  carbon  dioxide.  It  is  necessary 
to  measure  the  amount  of  free  carbon  dioxide  by  titrating,  say 

N 
200  cc.  of  the  water  with  ^  Na2CO3,   using  phenolphthalein 

as  indicator.  Each  cubic  centimeter  of  this  reagent,  therefore, 
represents  an  equivalent  of  0.001  gram  in  terms  of  CaCOs.1 

Therefore,  five  times  the  number  required  for  200  cc.  of  water 
would  represent  the  equivalent  in  1,000  cc.  or  1  liter  of  water. 
This  would  represent  milligrams  per  liter  which  is  the  same  as 
parts  per  million.  Parts  per  million  multiplied  by  0.0583  = 
grains  per  gallon.2 

The  " bicarbonate"  carbon  dioxide  is  determined  by  titrating 

N 
a  measured  volume  of  the  water  with  ^  sulphuric  acid,  using 

1  The  molecular  weight  of  CaCO3  is  100.     This  is  a  bivalent  molecule, 

hence,   the  univalent   or   hydrogen  equivalent  would  be  50  and  the   ~ 

oil 

value  would  be  1  gram  per  1000  cc.  Hence,  1  cc.  would  have  a  CaCO3 
equivalent  of  0.001  gram. 

2  One  gallon  weighs  58,330  grains  hence  |  QQQ  QQQ  of  a  gallon  or  1  part 
per  million  weighs  0.0583  grains. 


BOILER  WATERS  123 

methyl  orange  as  indicator  (see  p.  206,  Part  II).     Each  cubic 

N 
centimeter  of  y^   sulphuric   acid   is   equivalent   to  0.005  gram 

CaC03.  Therefore,  if  200  cc.  of  water  be  titrated,  each  cubic 
centimeter  of  acid  used  corresponds  to  0.025  grams,  that  is  25 
mg.  per  liter  or  25  parts  per  million  bicarbonate  carbon  dioxide, 
measured  in  terms  of  CaCOs. 

The  above  estimation  of  the  "free"  and  bicarbonate  carbon 
dioxide  would  represent  all  of  the  conditions  to  be  taken  into 
consideration  in  connection  with  the  lime  treatment  except  for 
the  slight  irregularity  in  the  behavior  of  one  element.  The 
magnesium  carbonate,  especially  in  the  presence  of  other  salts, 
is  soluble  to  an  extent  which  makes  it  advisable  to  carry  the 
reaction  one  step  further  and  provide  for  the  formation  of  mag- 
nesium hydroxide  which  compares  favorably  as  to  insolubility  with 
the  calcium  carbonate.  This  is  effected  by  adding  enough  extra 
Ca(OH)2  to  correspond  to  the  magnesium  present.  By  direct 
determination,  therefore,  of  the  magnesium  and  the  calculation 
of  the  same  to  the  calcium  carbonate  equivalent,  we  have  the 
necessary  correction  indicated  for  this  element.  By  adding  the 
calcium  carbonate  equivalent  thus  found  to  the  factor  as  derived 

N 
above  by  titration  with  ^  sulphuric  acid,  we  have  a  corrected 

calcium  carbonate  equivalent  for  the  bicarbonate  carbon  dioxide 
plus  the  magnesium  present. 

Having  thus  determined  the  amount  of  "excess"  and  bicar- 
bonate carbon  dioxide  plus  the  magnesium,  in  terms  of  CaCOs, 
the  amount  of  reagent  as  CaO  for  the  total  CaCOs  equivalent 
would  be  in  the  ratio  of  56  : 100.  To  transfer  to  a  unit  of  1,000 
gal.,  multiply  values  for  1  gal.  by  1,000;  and  to  transfer  grains  to 

1  ^\A 

pounds  avoirdupois,  divide  by  7,000.     Hence,  =  of  y^  or  0.08 

times  the  grains  per  gallon  of  total  calcium  carbonate  equivalent 
represents  the  pounds  of  CaO  reagent  needed  for  each  1,000  gal. 
of  water  in  removing  or  correcting  for  these  ingredients. 

In  the  case  of  common  or  commercial  reagents  used  in  water 
treatment,  the  impurities,  of  course,  must  be  allowed  for. 

Where  the  lime  is  added  in  the  form  of  a  clear  solution  of  Ca- 


124  FUEL,  GAS,  WATER  AND  LUBRICATION 

(OH)  2,  the  latter  is  dissolved  to  the  point  of  saturation  and  this 
concentrated  solution  becomes  the  reagent. 

The  solubility  of  CaO  is  about  78  grains  per  gallon  cold, 
(60°F.).  Hence  -fa  gal.  of  lime  water  contains  1  grain  of  CaO, 
and  —  ft-  would  represent  the  number  of  gallons  necessary  to 
hold  1  Ib.  of  CaO  in  solution.  Therefore, 

Number    of    gallons    satu- 
The  grams  ,    ,  ,.  , 

rated  lime  water  required 
7,000        8  per   gallon  ,,        ,11- 

-  X—  •    or  7.18  X    *    <5  ^r\  to  remove  the  total  calcium 

78          100  °i     Oav^Ua  =  ,  ,      , 

.     ,  carbonate    equivalent     in 

equivalent  ^  ga] 


The  solubility  of  CaO  decreases  as  the  temperature  of  the  water 
increases.  It  should  be  remembered,  also,  that  CaO  slakes  to 
Ca(OH)2  and  it  is  really  the  solubility  of  the  latter  compound 
which  is  involved.  Usually,  however,  the  reference  is  made  to 
the  solubility  of  CaO  as  the  basis.  Thus,  by  calculating  from 
Lamy's  tables  (C.  R.,  vol.  86,  p.  333), 

78  grains  CaO  will  saturate  1  U.  S.  gallon  at    60°F. 

70  grains  CaO  will  saturate  1  U.  S.  gallon  at    86°F. 

58  grains  CaO  will  saturate  1  U.  S.  gallon  at  112°F. 

51  grains  CaO  will  saturate  1  U.  S.  gallon  at  140°F. 

33  grains  CaO  will  saturate  1  U.  S.  gallon  at  212°F. 

Recently  the  market  has  come  to  be  supplied  with  pulverized 
dry  lime  in  the  hydrated  form.  To  find  the  solubility  by  weight 
of  this  material,  calculate  the  above  amounts  to  the  equivalent 
of  Ca(OH)2.  Thus, 

56*    :        74       ::     78       :        x 
CaO     Ca(OH)2     gr.CaO     gr.Ca(OH)2 

Whence,  78  grains  CaO  =  103  grains  Ca(OH)2,  which  would 
represent  the  solubility  per  gallon  at  60°F.  of  pure  material. 

Treatment  with  Soda  Ash,  Na2CO  3.  —  Of  the  substances  suffi- 
ciently cheap  to  be  available,  sodium  carbonate  or  "soda  ash"  is 
by  far  the  best  adapted  for  Division  II  of  Table  XVIII,  or  those 
ingredients  causing  the  permanent  hardness  of  the  water.  No 
reaction  or  change  in  solubility  by  heating  can  be  effective, 
though  many  attempts  to  remove  the  sulphate  by  reason  of  the 
less  solubility  of  calcium  sulphate  in  hot  water  (as  indicated  in 
Table  XV),  have  been  attempted.  With  this  class  of  substances, 
it  is  more  effective  to  remove  them  as  carbonates,  but  this  must  be 


BOILER  WATERS  125 

brought  about  by  the  addition  of  a  soluble  carbonate  salt,  the 
cheapest  of  which  is  sodium  carbonate  or  "soda  ash, "  Na2C03,  as 
above  indicated. 

To  measure  the  amount  of  "soda  ash,"  Na2C03,  necessary  for 
the  precipitation  of  the  sulphates  of  magnesium,  calcium,  andiron 
or  permanent  hardness,  read  carefully  Exercise  IX  on  page  213 
of  Part  II. 

The  reactions  involved  may  be  represented  as  follows: 

CaSO4  +  Na2CO3  =  CaC03  +  Na2SO4 
MgSO4  +  Na2CO3  =  MgCO3  +  Na2S04 

The  amount  of  "soda  ash"  used  up  in  this  reaction  is  directly  the 
measure  of  this  substance  to  be  used  in  treating  the  water. 
Thus,  if  200  cc.  of  water  were  taken,  then  five  times  the  number 

N 
of  cc.  of  JQ  Na2C03  X  0.0053  would  represent  the  weight  in 

grams  per  liter  of  Na2C03  required.  This  multiplied  by  1,000  = 
milligrams  per  liter  and  this  multiplied  by  0.0583  would  give  the 
grains  per  gallon  required  directly  in  terms  of  "soda  ash." 
Multiplying  this  by  one-seventh  would  give  the  number  of 
pounds  needed  per  thousand  gallons.  Where  magnesium  salts 
are  present  as  part  of  the  permanent  hardness,  the  MgC03 
formed  as  indicated  above  is  to  be  precipitated  as  Mg(OH)2, 
the  same  as  under  temporary  hardness.  Hence,  all  magnesium 
compounds  call  for  an  equivalent  of  Ca(OH)2  in  addition  to  the 
primary  reagent  needed.  This,  however,  is  provided  for  in  the 
method  of  analysis  which  determines  all  of  the  magnesium, 
whatever  the  form  in  which  it  is  present;  and  the  secondary 
reagent,  Ca(OH)2,  for  its  removal  has  been  considered  under  the 
preceding  topic;  viz.,  "Treatment  with  Lime."  A  double 
reaction  is  thus  provided  for  magnesium,  whether  the  combi- 
nation be  that  of  a  bicarbonate,  a  sulphate,  or  a  chloride. 

Treatment  with  Coagulants. — Coagulants  are  more  frequently 
employed  for  the  removal  of  bacterial  growths  and  the  correcting 
of  excessive  turbidity.  It  is  therefore  a  method  of  less  frequent 
application  in  waters  for  boiler  use.  However,  since  there  is  a 
positive  connection  between  suspended  matter  and  foaming  or 
priming  in  the  generation  of  steam,  the  removal  of  such  suspended 
matter  may  become  important.  Two  methods  may  be  employed. 


126 


FUEL,  GAS,  WATER  AND  LUBRICATION 


First,  the  precipitated  calcium  carbonate  and  magnesium 
hydrate  if  considerable  in  amount,  will  act  as  a  very  effective 
medium  for  carrying  down  finely  divided  solids  which  otherwise 
would  remain  for  a  long  time  in  suspension.  For  this  reason  it 
is  of  advantage  where  an  intermittent  process  is  employed  to  stir 


FIG.  23. — Eureka  water  softener,  continuous  system.1     The  description  of  the 
parts  can  be  seen  from  the  explanation  accompanying  Fig.  24. 

throughout  the  mass  of  water  the  bottom  sediment  from  previous 
reactions  just  before  the  addition  of  the  fresh  reagents.  There 
will  thus  be  accentuated  the  coagulating  and  settling  effect  of 
both  the  old  and  the  new  precipitates. 

Second,  if  ferrous  sulphate,  FeSO4,  or  aluminum  sulphate,  A12- 
(SO4)3,  is  added  to  the  raw  water  in  known  amount  and  an 

1  Supplied  by  the  Dodge  Manufacturing  Co.,  Mishawaka,  Ind. 


BOILER  WATERS 


127 


equivalent  increase  provided  in  making  up  the  calcium  hydroxide 
or  soda  ash,  the  result  will  be  the  formation  of  iron  hydroxide 
Fe(OH)2,  quickly  changing  to  the  red  ferric  hydroxide,  Fe(OH)3, 
the  corresponding  aluminum  hydroxide,  A1(OH)3.  These 


or 


FIG.  24. — Continuous  water  purification  apparatus.1 
A — Wood  fiber  filter  M — Reaction  chamber 

E — Overshot  water-wheel  N — Spiral  accelerator  plates 

G — Soda  ash  solution  tank  P — Sludge  catchers 

J — Lime  saturating  tank  Y — Treated  water  reservoir 

S  and  U — Flushing  valves 

coagulants  are  exceedingly  effective  in  carrying  down  suspended 
matter.     The  approximate  amount  usually  employed  is  1  grain 
per  gallon  or  about  1  Ib.  per  5,000  gal.  of  water.     The  equivalent 
1  Supplied  by  the  Dodge  Manufacturing  Co.,  Mishawaka,  Ind. 


128 


FUEL,  GAS,  WATER  AND  LUBRICATION 


quantity  of  reagent  required  over  and  above  the  calculated 
amount  for  the  scaling  matter  present  would  be  f  Ib.  of  soda  ash, 
Na2CO3,  or  f  Ib.  of  lime,  CaO,  or  f  Ib.  of  calcium  hydroxide, 
Ca(OH)2,  for  each  pound  of  ferrous  sulphate  employed. 

Industrial  Methods. — While  in  this  discussion  the  reactions 
involved   in   the   purification   of   water   have   been   considered 


FIG.  25. — Intermittent  purification  system,  as  used^by  the  Chicago  and 
Northwestern  Ry.  Co.1  The  pump  house  is  located  between  the  two  tanks. 
The  raw  water,  together  with  the  chemical  mixture,  is  delivered  into  the  tilting 
vessel,  p,  from  which  it  is  discharged  to  the  right  or  left  into  the  wooden  box  or 
trough,  r,  and,  r'.  These  troughs  are  provided  with  shut-off  gates,  so  that  the 
treated  water  may  be  delivered  entirely  into  one  tank  or  the  other. 

separately  and  as  two  distinct  processes,  in  practice  they  are 
combined  into  one  operation;  that  is,  the  calculated  amount  of 
lime  for  treating,  say,  1,000  gal.  of  raw  water  has  incorporated 
with  it  the  amount  of  soda  ash  as  indicated  by  the  sulphate  or 
permanent  hardness  per  1,000  gal.,  and  the  two  reagents  thus 
combined  are  added  directly  to  the  water. 

1  Designed  by  G.  M.  Davidson,  Chemist  and  Engineer  of  Tests,  Chicago 
&  Northwestern  Ry.  Co. 


BOILER  WATERS 


129 


Very  many  mechanical  devices  for  automatically  measuring 
the  correct  amount  of  each  reagent  are  in  use,  depending  in  the 
main  upon  the  principle  that  a  given  weight  or  volume  of  the 
incoming  raw  water  shall  operate  certain  mechanical  arrange- 
ments, whereby  the  proper  amount  of  chemical  is  discharged  into 
the  water.  The  devices  are  of  two  general  types — the  con- 
tinuous and  the  intermittent.  In  the  continuous  type  the  raw 


FIG.  26. — Chemical  mixing  and  measuring  device.1  The  chemical  is  delivered 
through  the  funnel,  n,  together  with  the  raw  water,  passing  through  the  pipe,  o, 
into  the  tilting  vessel,  p. 

water  flows  into  the  apparatus  and  is  discharged  in  the  purified 
form  ready  for  use.  In  the  intermittent  type  the  raw  water 
is  made  to  flow  through  a  mechanical  measuring  arrangement, 
whereby  the  chemicals  in  the  proper  proportion  are  added,  after 
which  the  water  is  brought  into  a  large  settling  tank  for  the  time 
element  to  enter  in  for  the  accomplishing  of  the  reaction  involved 
and  also  the  settling  out  of  the  precipitates.  Both  types  are 

1  Designed  by  G.  M.  Davidson,  Chemist  and  Engineer  of  Tests,  Chicago 
&  Northwestern  Ry.  Co. 


130 


FUEL,  GAS,  WATER  AND  LUBRICATION 


effective,  the  essential  point  in  any  case  being  that  the  automatic 
devices  for  measuring  the  reagents  be  exact  and  unfailing  in 
their  operation.  Illustrations  are  given  of  representative  devices 
for  each  type.  They  have  been  selected  primarily  with  reference 
to  their  adaptability  in  the  matter  of  illustrating  the  principles 
of  water  treatment  as  outlined  in  the  text. 


FIG.  27. — Chemical  mixing  and  measuring  device,  front  view.1 

Arguments  are  plentiful  for  the  adoption  of  some  form  of  water 
purification  for  practically  every  sort  of  industrial  use.  For 
domestic  and  laundry  purposes  the  softening  of  the  water  supply 
by  means  of  the  soap  employed  is,  theoretically  at  least,  far 
more  expensive  than  doing  the  same  work  with  soda-ash  and 
lime.  The  various  railway  systems  for  the  most  part  make  use 
of  purification  plants  for  their  service  waters.  One  company 
with  34  treating  plants  on  its  various  lines  shows  a  summary  for 
19 15  as  follows:2 

1  Designed  by  G.  M.  Davidson,  Chemist  and  Engineer  of  Tests,  Chicago 
&  Northwestern  Ry.  Co. 

2t Communicated  by  R.  C.  BARDWELL,  Chief  Chemist,  Union  Pacific  Ry., 
Kansas  City. 


BOILER  WATERS 

Total  consumption  treated  water,  gallons 604 , 468 , 087 

Total  scaling  material  removed  by  treatment, 

pounds 1,816,837 

Saving  in  fuel,  repairs,  etc.,  estimated  at  7  cents 

per  pound  of  incrustants  removed $127 , 171 . 00 

Cost  of  treatment,  labor,  chemicals,  maintenance, 

plus  10  per  cent,  on  investment 26,017.00 

Total  net  saving $100,454.00 

Cost  of  34  treating  plants $70,450.00 

TABLE  XVIII.— RATING  OF  BOILER  WATERS 
As  made  use  of  by  the  C.  B.  &  Q.  R.  R.,  W.  H.  WICHORST,  Engineer  of  Tests 

Incrusting  Rating 
The  figures  represent  parts  per  100,000. 

1.  Very  good — Water  having  sodium  carbonate,  and  hardness  less  than  35. 

2.  Good         — Water  having  sodium  carbonate,  and  hardness  greater  than 

35. 

Water  having  sulphate  hardness  less  than  5,  or  total  hardness 

less  than  20. 

3.  Fair  — Water  with  sulphate  hardness  between  5  and  10,  and  total 

hardness  less  than  30,  or  total  hardness  between  20  and  30. 

4.  Bad  — Water  with  sulphate  hardness  between  10  and  15,  and  total 

hardness  less  than  50,  or  total  hardness  between  30  and  50. 

5.  Very  bad  — Water  with  sulphate  hardness  greater  than  15,  or  total  hard- 

ness greater  than  50. 

Foaming  Rating 

(A)  Very  good — Alkali  salts  less  than  7. 
(B}  Good         — Alkali  salts  between    7  and  15. 

(C)  Fair  — Alkali  salts  between  15  and  25. 

(D)  Bad  — Alkali  salts  between  25  and  40. 

(E)  Very  bad  — Alkali  salts  over  40. 

Summary  of  Ratios. — In  the  preceding  discussion  the  various 
scaling  ingredients  have  all  been  reduced  to  the  CaC03  equiva- 
lent, chiefly  for  convenience  in  making  calculations  for  the 
amount  of  reagent  needed  in  treatment.  If,  however,  we  have  in 
hand  the  analysis  of  a  water  giving  the  hypothetical  combination 
as  the  various  ingredients  are  supposed  to  occur  in  the  water,  it 
will  be  found  more  convenient  to  make  use  of  a  table  of  factors, 
as  given  on  p.  219.  This,  in  the  main,  has  been  compiled  from 
the  Report  of  the  Committee  on  Water  Service  of  the  American 
Railway  Engineering  and  Maintenance  of  Way  Association,  em- 
bodied in  their  Bulletin  No.  83,  January,  1907.  See  also  The 
Hardness  of  Illinois  Municipal  Water  Supplies,  by  Dr.  Bartow, 
Proc.  Illinois  Society  of  Engineers  and  Surveyors,  1909. 


132 


FUEL,  GAS,  WATER  AND  LUBRICATION 


Standards  for  Indicating  Degrees  of  Hardness.  —  The  English 
degrees  of  hardness  on  Clark's  scale  as  it  is  usually  called,  repre- 
sent grains  per  Imperial  gallon;  that  is,  each  degree  is  1  part  per 
70,000.  Hence,  1  degree  of  hardness  by  the  Clark  scale  would  be 

'        or  1.2  degrees  per  U.  S.  gallon. 


It  is  usual  in  this  country  to  refer  hardness  as  well  as  the  other 
values  to  parts  per  million,  although  the  French  unit  is  sometimes 
used,  wherein  the  reference  is  to  parts  per  100,000. 

TABLE  XIX.  —  RELATIVE  VALUES  FOR  DEGREES  OF  HARDNESS 


Grains  per 
U.  S.  gallon 

Grains  per 
Imperial 
gallon 

French  unit 
or  parts  per 
100,000 

U.  S.  unit 
or  parts  per 
1,000,000 

1  part  per  1,000,000  
1  degree  Clark's  scale  

0.058 
1.20 

0.07 
1.00 

0.10 

1.43 

1.00 

14.30 

Limits  of  Purification. — It  should  be  borne  in  mind  that  at 
ordinary  temperatures  the  precipitated  material  is  soluble  to  the 
extent  of  3  to  5  grains  per  gallon.  Hence,  this  represents  the 
approximate  limit  to  which  scaling  matter  can  be  removed.  At 
higher  temperatures  the  solubility,  especially  of  the  magnesium 
product,  is  greatly  reduced.  So  that,  if  it  were  practicable  to 
raise  the  temperature  of  the  water  for  treatment  50°F.,  the 
residual  scale  forming  material  could  be  reduced  to  1  or  1.5 
grains  per  gallon.1 

Typical  Waters  and  Their  Treatment. — In  the  table  below  is 
given  the  composition  of  a  number  of  typical  waters  from  munici- 
pal supplies  in  Illinois,  together  with  the  calculated  amounts  of 
the  reagents  called  for  and  the  cost  of  the  same  calculated  on  the 
basis  of  lime  at  $6.00  per  ton  and  soda  ash  at  $6.00  per  100  lb.2 

Zeolites. — Certain  earthy  compounds  of  the  zeolitic  type  have 
the  property  of  removing  calcium  and  magnesium  from  water 
which  is  made  to  percolate  through  them.  These  compounds 
are  hydrate  d  double  silicates  of  aluminium  and  a  base  which  may 
be  an  alkali  or  an  alkaline  earth.  These  bases  are  readily  inter- 

1  POWERS,  W.  A.,  "  Water  Softening,"  Chief  Chemist,  Santa  Fe  Railway. 

2  DR.  BARTOW,  From  Hardness  of  municipal  water  supplies:  Proc.  111. 
Soc.  Eng.  and  Surv.,  1909. 


BOILER  WATERS  133 

changeable,  hence  their  adaptability  to  the  water  softening 
process.  For  example,  a  water  carrying  calcium  bicarbonate  in 
passing  through  such  a  compound  with  a  sodium  base  will 
exchange  one  molecule  of  CaO  for  2  molecules  of  NaHC03,  thus, 

2Si02.Al2O3.Na20.     +     CaH2(CO3)2     = 

Sodium  Zeolite  Calcium  Bicarbonate 

2Si02.Al203.CaO    +      2NaHC03 

Calcium  Zeolite  Sodium  Bicarbonate 

If  the  water  contained  calcium  sulphate  in  solution,  the  reaction 
would  take  place  in  similar  manner,  yielding  sodium  sulphate, 
Na2S(>4,  to  the  water  in  place  of  the  CaSC>4  originally  present. 
When  all  of  the  sodium  base  has  been  removed,  the  activity  of 
the  zeolite  ceases,  but  it  may  be  regenerated  by  passing  a  salt 
brine  through,  which  restores  it  to  its  original  activity. 

Artificial  zeolites  with  the  maximum  capacity  have  been 
devised  and  are  extensively  used  in  water  purification  systems 
under  the  name  of  "Permutit."1 

This  ability  to  interchange  bases  has  been  found  to  a  greater 
or  less  degree  in  many  natural  deposits  and  doubtless  is  the  most 
rational  explanation  for  the  very  widely  distributed  waters  of 
Class  I,  which  are  characterized  by  the  presence  of  free  sodium 
carbonate  and  temporary  hardness  only. 

The  first  water  of  this  type,  doubtless,  to  be  brought  to  the 
attention  of  chemists,  resulted  from  an  attempt  in  1884  to  sink 
a  coal  shaft  at  Urbana,  111.  At  a  depth  of  160  ft.,  the  shaft  was 
abandoned  on  account  of  quicksand  and  excessive  water.  The 
water  was  made  to  serve  as  city  supply  for  both  Urbana  and 
Champaign  by  putting  down  numerous  driven  wells  with  8-in. 
casings.  Two  new  wells  have  recently  been  put  down  with  24- 
and  30-in.  casings  respectively. 

This  initial  example  was  made  the  subject  of  some  interesting 
studies  at  the  University  of  Illinois  and  the  area  supplying  it  was 
fairly  well  outlined.2  Waters  of  this  type  are  now  known  to 
exist  and  have  been  developed  for  use  in  many  localities  through- 
out the  state.  This  is  very  well  shown  in  Table  XX,  where  12 

1  BAREETT,  J.  F.,  and  BARTOW,  EDWARD,  The  use  of  Permutit  in  water 
softening:  111.  State  Water  Surv.,  Bull.  13,  p.  307. 

2  PARR,  S.  W.,  The  service  waters  of  a  railway  system:  Jour.  Am.  Chem. 
Soc.,  vol.  28,  p.  640,  1906. 


134 


FUEL,  GAS,  WATER  AND  LUBRICATION 


TABLE  XX. — TABLE  SHOWING  THE  HARDNESS,  AND  THE  AMOUNT  OF 

TWENTY-EIGHT  ILLI- 


City,  town  and 
village 

Class 

Mineral  content  —  -parts  per  million 

Iron 

Res. 

Na2 
COj 

MgClz 

MgSO4 

MgCOs 

CaSO4 

CaCOs 

Amboy  

II 
I 
III 
II 
III 
II 
II 
I 
II 
I 
II 
I 
II 
II 
I 
I 
III 
II 
II 
III 
I 
I 
I 
II 

I 
II 
I 
I 

1.4 
8.4 
0.4 
1.8 
0.1 
1.6 
0.0 
1.0 

450 
464 
418 
366 
511 
1,070 
288 
1,044 
1,892 

68.6 

13.9 

25.8 

34.1 
65.0 
106.9 
346.0 
10.5 

156.0 
5.0 

44.5 
192.0 

37.1 
203.1 
251.1 
27.3 

5.3 
53.4 

118.4 
146.8 
50.2 
56.4 
63.3 

211.7 
210.4 
161.0 
189.0 
276.2 
436.5 
110.5 
101.4 
234.0 
53.4 
186.7 
195.4 
210.8 
276.0 
196.0 
168.4 
192.0 
259.2 
171.7 
100.9 
22.2 
77.6 
144.0 
174.4 

202.1 
182.4 
221.2 
180.7 

Atlanta  
Aurora  

Beardstown  

12.9 

Belvidere  

58.7 

22.1 

Bloomington  
Byron 

113.9 
72.7 
25.2 
27.4 
76.9 
69.6 
108.9 
20.2 
91.0 
89.0 
126.0 
23.1 

Cambridge             .  . 



Canton               .    .  . 

Carbondale  
Carrollton  

0.7 
0.2 
0.5 
0.1 
0.7 
0.5 
1.0 
0.7 
0.3 
tr. 
0.0 
0.2 
3.8 
0.4 
0.2 

1.8 
1.1 
2.7 
1.8 

2,198 
357 
617 
485 
1,106 
342 
730 
432 
1,689 
1,448 
202 
2,337 
414 
402 
339 

350 
370 
678 
392 

268.8 
168.9 

.... 

Chatsworth  

Danville  

D  wight 

Elgin 

17.0 
225.7 

3.1 

Farmer  City 

Freeport              .  .  . 

Galesburg         

352.6 

Harvey     

363.5 
140.2 
89.0 

55.7 

264.4 
46.2 

1.2 

Havana  

28.0 
24.6 
122.2 
77.0 
122.6 

63.5 
66.1 
117.6 
118.4 

Minonk  



Ottawa 

Polo 

Rantoul  
Springfield  
Trlono   

Urbana  

of  the  28  waters  listed  are  seen  to  be  of  this  type.  Notice  in 
each  case  the  total  absence  of  any  of  the  constituents  which  form 
permanent  hardness. 

In  his  study  of  the  Thanet  sands  and  chalk  deposits  of  the 
London  basin,  Thresh1  concludes  that  the  alkaline  waters  of  that 
region  result  from  the  reactions  occurring  as  a  result  of  contact 
with  that  material  which  he  shows  to  be  zeolitic  in  character. 


J.  C.,  "The  Examination  of  Waters  and  Water  Supplies," 
2d  Ed.,  p.  368,  1913. 


BOILER  WATERS 


135 


LIME  AND  SODA  ASH  REQUIRED  TO  SOFTEN  THE  WATER  FURNISHED  TO 
NOIS  MUNICIPALITIES 


Chem- 

Soda ash 

Lime 

icals 

Parts 

Grains 

Pounds 

Parts 

Grains 

Pounds 

Approxi- 
mate 

Remarks 

per 

per 

per 

per 

per 

per 

cost 

million 

gallon 

1,000  gal. 

million 

gallon 

1,000  gal. 

per  1,000 

gal. 

22.7 

1.3 

0.18 

288.0 

16.7 

2.40 

0.01560 

160-ft.  well 

349.3 

20.2 

2.90 

0.01450 

151-ft.  well 

45.4 

2.6 

0.37 

181.0 

10.5 

1.50 

0.01490 

2,250-ft.  well 

57.2 

3.3 

0.47 

211.2 

12.3 

1.75 

0.01815 

30-  and  90-ft.  wells 

118.7 

6.8 

0.97 

301.8 

17.5 

2.51 

0.02195 

1,800-ft.  well 

314.9 

18.3 

2.61 

405.3 

23.6 

3.37 

0.06905 

Well  No.  1,  60  ft. 

9.2 

0.5 

0.07 

218.2 

12.7 

1.81 

0.02345 

2,000-ft.  well 

184.5 

10.7 

1.53 

0  .  00765 

1,380-ft.  well 

137.4 

79.8 

1.14 

237.2 

13.8 

1.97 

O.J03265 

l,646-and2,042-ft. 

208.4 

12.1 

1.73 

0.00865 

410-ft.  well 

4.4 

0.2 

0.03 

209.1 

12.1 

1.74 

0.00930 

Spring 



291.2 

16.9 

2.42 

0.01210 

1,285-ft.  well 

39.2 

2.2 

0.32 

283.5 

16.4 

2.36 

0.01820 

167.4 

9.7 

1.39 

270.8 

15.7 

2.25 

0.03905 

136-ft.  well 

230.7 

13.4 

1.91 

0.00955 

1,300-ft.  well 

331.8 

19.2 

2.76 

0.01380 

176-ff  well 

36.1 

2.1 

0.30 

294.0 

17.1 

2.45 

0.01825 

Before  filtration 

178.9 

10.3 

1.48 

270.4 

15.7 

2.25 

0.04085 

1,252-ft.  well 

495.9 

28.8 

4.12 

213.1 

12.4 

1.77 

0.09125 

1,680-ft.  well 

25.3 

1.4 

0.21 

107.1 

6.2 

0.89 

0.00865 

72-ft.  well 

237.3 

13.8 

1.97 

0.00985 

1,850-ft.  well 

280.0 

16.3 

2.33 

0.01165 

180-ft.  well 

230.1 

13.4 

1.91 

0.00955 

1,200-ft.  well 

4.6 

0.2 

0.03 

263.1 

15.3 

2.19 

0.01155 

1,200-  and  2,100-ft. 

wells 

227.0 

13.2 

1.89 

0.00945 

120-ft.  well 

47.0 

2.7 

0.39 

214.9 

12.4 

1.78 

0.01670 

420.0 

24.4 

3.50 

0.01750 

157-ft.  well 

283.0 

16.4 

2.36 

0.01180 

160-ft.  well 

Numerous  other  regions  in  England  are  known  to  yield  similar 
waters.  This  explanation  is  doubtless  applicable  also  to  the 
waters  of  the  same  type  so  frequently  occurring  in  the  drift 
deposits  of  the  Mississippi  Valley. 

In  the  steam  generator,  the  sodium  carbonate  of  these  natural 
waters  hydrolysis  to  a  very  considerable  extent,  forming  caustic 
soda,  NaOH.  After  excessive  concentration,  leaks  are  likely  to 
develop,  where,  due  to  further  concentration,  action  between  the 
caustic  and  the  metal  may  result  in  an  embrittlement  and  crack- 


136  FUEL,  GAS,  WATER  AND  LUBRICATION 

ing  of  the  boiler  plate  in  the  immediate  vicinity  of  these  leaks.1 
A  number  of  boiler  explosions  have  been  fairly  well  demon- 
strated to  have  resulted  from  such  embrittling  effect.  However, 
in  water  treatment  where  a  resulting  excess  alkalinity  occurs 
there  is  formed  also  an  equivalent  of  sodium  sulphate  which 
either  because  of  its  diluting  or  inhibiting  effect,  prevents  the 
development  of  cracks.  This  also  seems  to  be  the  status  of 
waters  artificially  treated  by  zeolitic  material. 

1  PARR,  S.  W.,  The  embrittling  action  of  sodium  hydroxide  on  soft  steel: 
Univ.  of  111.  Eng.  Exp.  Sta.,  Bull.  94,  1917. 


CHAPTER  XVIII 
LUBRICANTS 

Introduction. — "Next  to  the  conservation  of  the  world's  fuel 
supply  there  is  probably  no  subject  of  greater  importance  in  the 
manufacturing  world  than  the  control  of  waste  power  caused  by 
imperfect  lubrication  and  needless  friction.  .  .  .  Archbutt 
has  stated  that  of  the  10,000,000  hp.  in  use  in  the  United  King- 
dom of  Great  Britain  considerably  more  than  half  this  amount, 
40  to  80  per  cent  of  the  fuel,  is  spent  in  overcoming  friction, 
and  that  a  considerable  proportion  of  this  power  is  wasted  by 
imperfect  or  faulty  lubrication."1 

Any  substance  made  use  of  for  the  lessening  of  friction  is  called 
a  lubricant.  By  its  use  the  surfaces  of  sliding  bodies  are  sepa- 
rated by  a  thin  film  which  permits  of  easier  movement  than  if 
the  surfaces  were  in  direct  contact.  Lubricants  must,  therefore, 
vary  widely  for  the  different  kinds  of  work  involved.  For 
example,  the  "body"  must  be  suited  to  the  load.  Working 
temperatures,  both  high  and  low,  must  be  provided  for.  Oxi- 
dizing or  gumming  must  not  be  a  property  of  the  material,  and 
any  tendency  to  corrode  the  metal  surfaces  must  be  absent. 

Lubricants  are  derived  from  two  main  sources : 

1.  Oils  of  animal  or  vegetable  origin. 

2.  Mineral  oils. 

Animal  and  Vegetable  Oils. — All  oils  of  this  class  are  saponifi- 
able.  That  is,  they  are  compounds  of  fatty  acids  and  glycerine. 
They  decompose  to  a  considerable  extent  on  long  standing,  set- 
ting free  the  fatty  acids.  Many  vegetable  oils,  as  linseed  oil, 
readily  oxidize,  forming  a  gumming  substance.  Only  non- 
oxidizable  oils  are  suitable  for  lubrication.  Among  vegetable 
oils  the  best-known  illustrations  are  olive  (sweet)  oil  and  castor 
oil.  Among  animal  oils,  lard  oil  is  perhaps  the  most  common. 

Mineral  Oils. — These  oils  are  derived  from  petroleum  by  distil- 
lation.    They   will   not   saponify,    having   no    combination    of 
,  C.  F.,  Jour.  Ind.  and  Eng.  Chem.,  vol.  2,  p.  115,  1910. 
137 


138  FUEL,  GAS,  WATER  AND  LUBRICATION 

fatty  acids,  and  they  will  not  oxidize  to  form  " gumming" 
compounds. 

Compounded  Oils. — The  compounding  of  oils  is  an  attempt  to 
render  a  certain  oil  more  effective  by  mixing  with  another  oil 
having  slightly  different  properties.  Thus,  mineral  oils  may  be 
said  to  be  compounded  with  an  animal  oil  to  impart  greater 
body  or  viscosity  to  the  mixture;  or,  a  vegetable  oil  with  heavy 
body  but  too  little  fluidity,  may  be  compounded  with  a  mineral 
oil  to  improve  its  property  in  that  direction.  The  peak  of  the 
viscosity  effect  produced  by  compounding  a  vegetable  oil  with 
a  mineral  oil  is  obtained  with  relatively  low  percentages  of  the 
vegetable  oil,  probably  not  over  2  or  3  per  cent.  Beyond  this 
point  the  further  addition  of  the  vegetable  oil  may  add  an  expense 
out  of  proportion  to  the  benefit  obtained.  Mineral  oils  are 
often  compounded  with  each  other  to  produce  certain  desired 
properties.  Greases  are  mixtures  of  heavy  oil  residues  or  vaseline- 
like  substances  with  mineral  soap,  such  as  lime  soap,  to  the  extent 
of  30  to  40  per  cent,  thus  giving  a  mixture  of  great  body  for 
heavy  machinery,  shafting,  gears,  etc.  Finely  pulverized  mica 
or  graphite  is  also  similarly  employed.  Graphite  especially 
lends  itself  to  numerous  combinations  for  the  production  of  lubri- 
cants with  specific  properties.  An  interesting  variation  from 
the  usual  types  is  found  in  "Aquadag"  and  "Oildag"  wherein 
the  graphite  is  so  minutely  divided  that  it  is  possible  by  use  of 
proper  dispersoids  to  form  permanent  emulsions  with  both 
water  and  oil.  This  property  suggested  to  Mr.  Acheson,  who 
developed  the  material,  the  designation  of  "  Deflocculated  Ache- 
son  Graphite;"  hence  the  term,  "Oildag,"  etc. 

For  high  temperature  service  the  problem  becomes  more 
difficult.  An  oil  must  be  selected  which  will  not  volatilize  at  the 
high  temperature  employed.  The  principal  tests  in  the  exami- 
nation of  oils  have  for  their  purpose  the  development  of  these 
various  properties,  for  example,  the  viscosity  and  body  as  shown 
by  the  viscosimeter  and  specific  gravity,  the  flash  point  for  high 
temperature  use,  acid  or  saponification  number  to  show  whether 
or  not  the  oil  is  compounded  with  animal  or  vegetable  material. 

Because  of  their  low  cost  and  the  ease  with  which  they  may  be 
varied  to  meet  the  different  conditions  as  to  load,  speed  and 
temperature,  petroleum  and  the  products  which  may  be  derived 


LUBRICANTS  139 

therefrom  have  come  to  predominate  in  the  entire  field  of  lubri- 
cants. Hydrocarbons  of  the  general  type,  CnH2n+2  or  the  paraf- 
fin series  are  probably  best  suited  for  lubrication  purposes. 
However,  because  of  the  development  of  processes  for  distilling, 
cracking,  and  mixing  it  would  be  impossible  to  prescribe  a 
chemical  composition  to  conform  to  any  specific  type  of  carbon 
compounds.  Doubtless  some  forms  are  more  unstable  than 
others  and  as  a  rule,  in  service  at  high  temperatures  as  with  auto- 
mobiles, there  is  a  tendency  toward  decomposition  which  is 
almost  always  accompanied  by  the  formation  of  free,  or  perhaps 
more  properly,  colloidal  carbon.  Promoters  of  petroleum  lubri- 
cants, however,  who  claim  their  special  oils  are  without  any 
carbon  in  their  composition,  have  more  zeal  than  chemical  sense. 
Testing. — The  most  common  and  the  best  established  tests 
for  indicating  the  suitability  of  an  oil  for  lubricating  purposes  are 
the  following: 

(a)  Specific  gravity. 

(6)  Flash  and  fire  test. 

(c)  Viscosity. 

(d)  Free  acid. 

(e)  Saponification  number. 
(/)  Maumene  test. 

(g)  Conradson  test  for  carbonization. 
(h)  Emulsification. 

Specific  gravity  is  directly  an  indication  of  the  adaptability  of 
the  oil  to  the  load.  Light  machinery  requires  a  light  oil.  Heavy 
machinery  should  be  supplied  with  an  oil  of  not  less  than  0.885 
sp.  gr. 

Flash  and  fire  test  are  somewhat  related  to  specific  gravity  but 
perhaps  are  of  more  value  as  indicating  the  care  with  which  the 
lubricant  was  prepared.  It  is  also  an  index  of  the  adaptability 
of  the  oil  to  use  where  high  temperatures  are  involved,  as  in  the 
internal-combustion  motor,  the  high-pressure  steam  engine  and 
the  steam  turbine. 

Viscosity  is  more  directly  related  to  specific  gravity.  It  is  due 
to  the  internal  friction  of  the  oil  itself  and  must  increase  in 
amount  with  the  load  of  the  moving  parts.  No  attempt  is 
made  to  measure  the  viscosities  of  lubricants  in  terms  of  the 
viscosity  of  water  as  unity,  that  is,  by  factors  which  would  repre- 


140  FUEL,  GAS,  WATER  AND  LUBRICATION 

sent  specific  viscosities.  Special  instruments  have  been  designed 
which  give  arbitrary  factors  only.  The  end  sought  has  been  to 
devise  a  method  which  would  give  results  which  were  consistent 
as  to  their  relative  values  and  which  could  be  reproduced  with  a 
fair  degree  of  accuracy.  For  this  reason  the  viscosity  number  is 
meaningless  unless  accompanied  with  the  name  of  the  instrument 
by  which  it  was  determined. 

Free  acid  results  from  carelessness  in  the  refining  process. 
It  is  therefore  presumably  sulphuric  acid  or  sulphonic  organic 
compounds  formed  from  the  unsaturated  hydrocarbons.  Either 
substance  is  strongly  corroding. 

Saponification  serves  as  a  means  for  indicating  the  amount  of 
animal  or  vegetable  oil  used  in  compounding.  This  with  the 
Maumene*  test  may  serve  as  a  fairly  reliable  method  for  indi- 
cating the  kind  of  fatty  oil  entering  into  the  mixture. 

The  Conradson  test  is  an  attempt  to  measure  the  tendency  of 
an  oil  to  break  down  and  deposit  free  carbon  under  ordinary 
lubricating  conditions.  It  is  based  on  the  theory  that  upon 
evaporating  a  given  oil  to  complete  dryness,  the  residue  of 
carbon  remaining  will  furnish  an  index  of  the  tendency  of  the  oil 
to  decompose  or  change  its  chemical  composition  in  use. 

Emulsification  is  a  property  especially  to  be  considered  in 
those  systems  of  lubrication  which  circulate  the  oil  under  pressure 
and  require  that  it  be  collected  in  a  filtering  and  settling  chamber 
for  recirculating  through  the  moving  parts.  It  is  a  ready  means 
for  indicating  a  pure  hydrocarbon  oil  as  distinct  from  one  carry- 
ing impurities,  especially  mixtures  containing  sulphonic  residues 
or  the  saponified  salts  of  organic  acids  such  as  calcium  or  magne- 
sium soaps.  After  extended  investigation  into  the  significance  of 
emulsification,  the  American  Society  for  Testing  Materials  has 
included  this  test  in  its  standards  for  indicating  the  purity  or 
adaptability  of  lubricating  oils  for  specific  purposes.  For  some 
uses  as  with  screw  cutting  machines,  an  emulsifying  oil  is  desired. 
For  forced  feed  systems  a  demulsifying  oil  is  essential. 


PART  II 
LABORATORY  METHODS 

CHAPTER  XIX 

THE  PROXIMATE  ANALYSIS  OF  COAL 

Introduction. — The  procedure  as  here  outlined  for  the  proxi- 
mate analysis  of  coal  follows  substantially  the  final  report  on 
methods  of  analysis  as  adopted  by  the  joint  .committee  of  the 
American  Chemical  Society  and  the  American  Society  for  Testing 
Materials.1  The  preliminary  report  of  this  committee2  contains 
much  detail  of  value  relating  to  sources  of  error  and  general 
conditions  to  be  observed  in  the  procuring  of  accurate  results. 
The  final  report  is  in  a  much  more  condensed  form  and  is 
intended  as  a  guide  for  every-day  procedure  in  connection  with 
coal  contracts  and  inspection. 

The  Laboratory  Sample. — The  preparation  of  a  working  sample 
for  the  various  analytical  processes  must  be  carried  out  with 
special  reference  to  the  chief  considerations  which  govern  the 
taking  of  the  gross  sample.  For  example,  there  must  be  main- 
tained an  even  distribution  of  impurities  throughout  the  sample. 
A  certain  ratio  of  size  of  particles  to  size  of  sample  must  be 
observed.  If  the  gross  sample  as  it  conies  to  the  laboratory  is 
not  over  5  Ib.  in  amount  the  entire  sample  should  be  fine  enough 
to  pass  a  i-in.  screen.  This  means  that  the  largest  particle  will 
have  a  dimension  not  greater  than  T\  or  J  in.  Similarly  the 
working  sample  of  approximately  60  grams  must  be  sufficiently 
fine  to  pass  a  60-mesh  sieve.  With  this  reduction  in  size  the 
tendency  to  segregate  is  increased  and  the  opportunity  for 
moisture  changes  is  greatly  augmented.  This  is  an  especially 

1  Report  of  Committee  E-4,  Yearbook  Am.  Soc.  for  Testing  Mat.,  p.  596* 
June,  1915. 

2  Jour,  of  Ind.  and  Eng.  Chem.,  vol.  5,  p.  517,  1913.     Published  also  in 
Proc.  Am.  Soc.  for  Testing  Mat.,  vol.  14,  p.  412,  1914. 

141 


142  FUEL,  GAS,  WATER  AND  LUBRICATION 

important  feature  to  keep  in  mind  in  working  with  Illinois  coals 
which  have  an  initial  free  moisture  factor  at  the  time  of  breaking 
out  of  the  seam  of  from  5  to  15  per  cent.  These  coals  also  absorb 
oxygen  rapidly,  especially  when  finely  divided  and  at  slightly 
elevated  temperatures.  This  is  the  chief  factor  in  deterioration 
and  loss  of  heating  value.  The  freshly  prepared  sample  will  be 
found  to  give  higher  values  than  an  old  one. 

Moisture  Loss  on  Air  Drying. — Spread  the  "  as-received  "  four- 
mesh  sample  to  a  depth  of  J  to  f  in.  on  a  weighed  pan  about  18 
by  18  in.  by  1  \  in.  in  depth.  Weigh  and  air  dry  at  room  tem- 
perature or  in  a  special  drying  oven  through  which  a  current  of 
air  is  circulated  and  in  which  the  temperature  is  maintained  at 
10  to  15°C.  above  that  of  the  room.  Weigh  again  after  12  to  24 
hr.  The  moisture  content  should  now  be  in  approximate  equi- 
librium with  the  moisture  of  the  air.  This  will  mean  a  moisture 
factor  of  from  3  to  5  per  cent.  It  may  be  indicated  by  the  fact 
that  a  continuation  of  the  drying  process  will  not  show  a  loss  of 
more  than  0.1  per  cent  per  hour.  Note  the  loss  of  moisture  on 
air-drying  and  calculate  to  per  cent  of  the  entire  sample  as 
received. 

Working  Sample. — Pass  the  air-dried  sample  entire  at  once 
after  final  weighing  through  a  grinder  of  the  coffee-mill  type  set 
to  grind  to  about  20-mesh.  Immediately  after  passing  through 
the  grinder,  mix  and  riffle  down  to  about  500  grams  and  transfer 
to  a  porcelain  jar  of  an  Abbe  ball  mill.  The  jar  should  be  not 
over  one-third  full  of  pebbles  and  the  coal  sufficient  in  amount  to 
have  a  partial  cushioning  effect  so  the  pebbles  will  not  strike  too 
harshly  upon  the  wall  of  the  jar.  A  measurable  increase  in  ash 
may  result  from  abrasion  of  the  jar.  The  coal  should  be  pulver- 
ized to  60  mesh  which  will  be  complete  for  bituminous  coals 
in  about  \  hr.  The  jar  should  turn  at  about  60  r.p.m.  Separate 
the  pebbles  on  a  coarse  sieve,  mix  and  riffle  the  coal  to  a  labora- 
tory working  sample  of  about  60  grams,  all  of  which  should  pass 
a  60-mesh  sieve.  The  sample  is  put  in  a  4-oz.  bottle  and  closed 
with  rubber  stopper.  The  time  occupied  from  the  opening  of 
the  jar  to  the  final  enclosing  of  the  sample  should  not  be  over  2  or 
3  min. 

Moisture  in  the  Laboratory  Sample. — Determine  the  moisture 
on  the  60-mesh  working  sample,  by  weighing  out  1  gram  in  a 


THE  PROXIMATE  ANALYSIS  OF  COAL  143 

glass  capsule  and  drying  with  the  cover  off  at  104  to  110°C.  for 
1  hr.  Replace  the  cover,  cool  in  the  desiccator  and  weigh.  The 
loss  of  weight  is  the  amount  of  water  in  the  sample.  Save  for 
ash  determination.  This  sample  is  used  for  all  of  the  analytical 
determinations.  Calculate  each  value  except  the  moisture  factor 
to  the  dry  basis. 

Total  Moisture  (a). — The  value  for  total  moisture  on  the 
sample  "  as-received "  is  obtained  by  combining  the  loss  on  air 
drying  with  the  moisture  factor  found  on  the  air-dry  sample  as 
just  described.  These  two  factors  cannot  be  added  of  course 
until  brought  to  the  same  basis  of  reference.  Calculate  the 
moisture  found  in  the  air  dry  sample  to  the  percentage  it  would 
be  of  the  original  coal  "as  received"  and  add  to  the  loss  on  air 
drying.  This  will  give  the  total  moisture  percentage.  Special 
attention  should  be  given  to  methods  of  calculation  discussed 
under  "  Calculations "  at  the  end  of  the  chapter. 

Total  Moisture  (6). — Another  method  whereby  the  total  "as- 
received"  moisture  is  obtained  directly  and  which  also  has 
certain  advantages  and  is  probably  in  more  general  use  is  as 
follows :  Immediately  after  passing  the  5-lb.  gross  sample  through 
the  coffee-mill  grinder  for  reduction  to  10-  to  20-mesh  size,  it  is 
spread  out  in  a  shallow  pan  and  by  means  of  a  spoon  a  60-gram 
sample  is  taken  from  various  parts.  This  is  placed  without  siev- 
ing in  a  rubber-stoppered  bottle  and  labeled  "For  Total  Moisture." 
Weigh  5  grams  into  a  shallow  aluminum  dish  with  suitable  glass 
cover  and  heat  with  the  cover  off  for  1J  hr.  at  104  to  110°C. 
Cover  and  cool  in  a  desiccator  over  concentrated  sulfuric  acid 
sp.  gr.  1.84.  The  loss  in  weight  calculated  to  per  cent,  represents 
the  total  moisture  of  the  coal  "as-received." 

The  main  portion  of  the  sample  is  air-dried  in  a  shallow  pan  as 
described  under  that  paragraph  but  without  regard  to  moisture 
loss.  When  the  moisture  content  is  reduced  to  3  to  5  per  cent, 
the  sample  is  thoroughly  mixed  and  reduced  by  riffling  to  about 
120  grams.  It  is  then  pulverized  by  any  suitable  method  to  60- 
mesh,  and  the  moisture  determined  by  oven  drying  at  104  to 
110°C.  as  described  under  "Moisture  in  the  Laboratory  Sample." 

Ash  (a). — Transfer  the  1  gram  of  coal  remaining  in  the  glass 
capsule  from  the  moisture  determination  to  a  shallow  porcelain 
ashing  dish.  Place  on  a  triangle  2  or  3  in.  above  a  Bunsen  flame. 


144 


FUEL,  GAS,  WATER  AND  LUBRICATION 


It  can  be  left  in  this  condition  without  attention  for  15  or  20  min., 
when  most  of  the  carbonaceous  matter  will  have  been  burned  off. 
Lower  the  ashing  dish  to  within  J  or  J  in.  of  the  flame  and  leave 
without  attention  for  an  equal  length  of  time.  Occasional  stirring 
with  a  platinum  or  Illium  wire  will  facilitate  the  oxidation. 
Finally  place  the  capsule  in  a  muffle  maintained  at  a  dull  or 
cherry  red  temperature  at  700  to  750° C.  Ten  minutes  in  the 
muffle  should  be  ample  for  burning  off  the  last  traces  of  carbon. 
If  special  ashing  dishes  and  a  muffle  are  not  available,  a  porcelain 
crucible  and  No.  5  Meker  burner  may  be  used  but  special  care 
should  be  given  to  the  temperature  employed  and  sufficient  time 
allowed  with  occasional  stirring  to  insure  complete  burning  out 
of  all  carbonaceous  matter.  Cool  in  the  desiccator  and  weigh. 
Subtract  the  weight  of  the  crucible  and  compute  the  weight  of  the 
ash  to  percentage  of  air  dry  coal. 


500 

B 
I 

.5  400 
| 

S  300 

a 

§  200 
> 

100 


=?: 


600 


700 


900 


800 

Degrees  centigrade 

Dissociation  of  calcium  carbonate 

Eeisenfeld  1909 

FIG.  28. 


Ash  (6). — It  occasionally  occurs  that  Illinois  coals  are  met 
with,  having  a  percentage  of  CaCO3,  which  makes  it  advisable  in 
careful  work,  especially  where  unit  coal  values  are  involved,  to 
modify  the  usual  method  for  the  determination  of  ash.  When 
the  C02  value,  for  example,  exceeds  1  per  cent,  or  when  the 


THE  PROXIMATE  ANALYSIS  OF  COAL 


145 


calcite  is  in  excess  of  about  2  per  cent,  these  modifications 
should  be  observed.  The  reason  is  obvious.  The  combination 
of  FeS2  and  CaC03  in  the  process  of  ashing  produce  Fe2O3  and 
CaS.  The  latter,  however,  slowly  oxidizes  to  CaS04  It  is  the 
uncertainty  as  to  the  completeness  of  this  change  which  makes  it 
advisable  to  proceed  as  follows: 

After  the  preliminary  burning  off  of  the  carbon  and  cooling, 
the  ash  is  moistened  with  a  few  drops  of  sulfuric  acid  (diluted 
1:1)  and  after  careful  application  of  heat  to  avoid  spurting,  is 
heated  to  700  to  750°C.  and  retained  at  that  temperature  for 


100 


7UU 


11U) 


1200 


800  900  11)00 

Degrees  centigrade 
Decomposition  of  calcium  sulphate  at  various  temperatures 

FIG.  29. 

3  to  5  min.  Cool  in  a  desiccator  and  weigh.  Three  times  the 
equivalent  of  carbon  present  as  CaCO3  is  subtracted  from  the  ash 
as  weighed  in  order  to  restore  the  weight  of  the  CaS04  formed  to 
the  equivalent  of  CaC08.  That  is, 

S08  =  80 
3C  =  36 
80  -  36  =  44,  C02  equivalent 

By  reference  to  the  dissociation  temperatures  at  normal  pressure, 
Fig.  28,  for  calcium  carbonate  it  is  evident  that  it  would  be 
futile  to  attempt  to  ash  a  high  calcite  coal  at  a  temperature 
sufficiently  low  to  avoid  decomposition  of  the  CaC03.  By 
10 


146  FUEL,  GAS,  WATER  AND  LUBRICATION 

reference  to  Fig.  29,  however,  it  is  evident  that  a  complete  transfor- 
mation of  the  CaCO3  to  CaS04  would  permit  the  use  of  a  tem- 
perature of  700°  without  loss.1 

Volatile  Matter,  Official  Method.— The  official  method  for 
determining  the  volatile  matter  in  coal  as  indicated  by  the  joint 
committee  on  coal  analysis  in  the  Journal  of  Industrial  and 
Engineering  Chemistry2  prescribes  the  use  of  a  platinum  crucible 
with  capsule  cover  fitting  inside  of  the  crucible,  that  is,  telescoping 
|  to  i  in.,  instead  of  an  ordinary  cover  resting  on  the  upper 
edge.  The  crucible  with  1  gram  of  coal  is  placed  in  a  muffle 
maintained  at  950°C.  (  +  20°C.)  A  vertical  electrically  heated 
muffle  is  easy  of  construction  and  very  satisfactory  for  this  work. 
On  account  of  the  variation  in  pressure  and  heating  value  of  city 
gas  it  is  difficult  to  obtain  consistent  results  with  the  Bunsen  or 
Meker  burners.  A  muffle  heated  by  gas  and  maintained  at  the 
proper  temperature  is  much  to  be  preferred  to  heating  by  the 
direct  flame.  On  account  of  the  expense  of  platinum,  the  use  of 
an  Illium  crucible  may  be  substituted  in  class  work  as  indicated 
below. 

It  is  to  be  noted  that  any  method  which  retards  the  trans- 
mission of  heat  to  the  coal  will  result  in  a  lower  indicated  amount 
for  volatile  matter,  and  a  correspondingly  higher  percentage  for 
fixed  carbon.  The  Illium  alloy  should  give  the  same  values  as 
when  using  platinum.  In  the  absence  of  a  suitable  muffle  it 
may  be  possible  to  make  use  of  the  flame  of  a  large  Meker  burner. 
By  means  of  a  thermocouple  it  should  be  determined  that  the 
flame  temperature  of  the  gas  used  is  well  above  900° C.  and  a 
burner  used  of  sufficient  size  to  completely  envelop  the  Illium 
crucible  and  capsule  cover.  This  is  fairly  well  accomplished  by 
use  of  the  No.  5  Meker  burner.  Where  porcelain  crucibles  are 
the  only  ones  available  the  discrepancies  from  the  official  values 
are  apt  to  be  large.  Fairly  satisfactory  results  may  be  obtained, 
however,  by  use  of  a  No.  5  Meker  burner  and  accumulating  an 
advance  heat  supply  as  indicated  in  the  next  paragraph. 

Volatile  Matter,  Porcelain  Crucible  Method. — Select  a  porce- 
lain crucible  with  well-fitting  cover,  ignite,  with  cover,  in  the 
flame  of  a  No.  5  Meker  burner  to  a  dull-red  heat,  cool  in  the 

1  111.  State  Geol.  Surv.  Coop.,  Bull  3,  pp.  30-36. 

2  Vol.  5,  p.  522,  1913. 


THE  PROXIMATE  ANALYSIS  OF  COAL  147 

desiccator  and  weigh.  Place  a  nichrome  triangle  over  the  burner 
and  over  the  triangle  place  an  inverted  20-gram  assay  crucible 
with  the  bottom  ground  off,  exposing  a  hole  approximately  1  in. 
in  diameter.  When  this  apparatus  is  heated  to  as  high  a  tem- 
perature as  possible,  remove  the  inverted  crucible,  put  in  place 
the  porcelain  crucible,  with  cover  on,  containing  the  1  gram  of 
air-dry  coal,  and  restore  at  once  the  prepared  assay  crucible. 
Continue  the  heating  for  7  min.  and  at  the  end  of  the  period  turn 
off  the  flame  and  remove  the  assay  crucible  but  do  not  disturb 
the  cover  of  the  porcelain  crucible  until  the  same  has  been  reduced 
below  a  red  heat.  Transfer  to  a  desiccator,  cool  and  weigh  with 
the  cover.  The  loss  in  weight  minus  the  moisture  present  is  the 
weight  of  volatile  matter. 

Fixed  Carbon. — The  sum  of  the  percentages  for  moisture, 
(on  the  air-dry  or  working  sample)  ash,  and  volatile  matter, 
subtracted  from  100,  will  leave  as  a  remainder  the  percentage  of 
fixed  carbon  in  the  air-dry  coal. 

Calculations. — A  type  of  computation  is  constantly  employed 
in  connection  with  fuel  analysis,  which,  while  exceedingly  ele- 
mentary, seems  not  to  have  been  encountered  by  the  average 
.  student  in  his  public  school  work.  Or  possibly  these  simple  arith- 
metical concepts,  once  familiar,  have  been  forgotten  because  of 
the  lack  of  even  occasional  contact.  It  is  urged  that  the  student 
revive  his  acquaintance  with  them  to  the  point  of  genuine 
familiarity. 

The  working  sample  of  coal  which  is  used  in  all  of  the  analytical 
processes  has  been  brought  into  approximate  equilibrium  with  the 
air  so  that  its  content  of  moisture  will  not  appreciably  change 
during  the  process  of  weighing  out  the  amount  to  be  taken  for 
each  determination.  The  preparing  of  this  air-dry  sample  is 
therefore  for  the  purpose  of  securing  greater  accuracy  in  weighing 
and  is  a  matter  of  particular  concern  to  the  chemist  only.  The 
results  obtained  on  that  unusual  or  specific  sample  are  of  use  to 
no  one  else  and  should  not  be  reported  in  that  form.  They  must 
be  calculated  either  to  the  dry,  that  is  the  "  moisture  free,"  basis, 
or  to  the  wet,  that  is  the  " as-received"  basis,  or  more  commonly, 
both  sets  of  values  are  included  in  the  report. 

To  transfer  values  obtained  on  the  air-dry  sample  to  the  dry 
basis,  the  moisture  factor  is  eliminated  and  the  resulting  values 


148  FUEL,  GAS,  WATER  AND  LUBRICATION 

total  100  per  cent.  Each  value  obtained  on  the  air-dry  basis 
therefore  is  divided  by  1  minus  the  content  of  moisture. 

The  values  obtained  on  the  air-dry  sample  contain  a  moisture 
factor  and  total  100  per  cent.  To  transfer  them  to  the  "  as- 
received  "  basis  there  is  to  be  restored  the  moisture  lost  on  air- 
drying.  The  resulting  values,  including  all  the  moisture,  must 
total  100  per  cent.  The  new  values  are  computed  therefore  by 
multiplying  the  air-dry  values  by  1  minus  the  loss  on  air  drying. 
Note,  however,  that  the  sum  will  not  equal  100  per  cent  unless 
that  process  is  applied  to  the  moisture  factor  of  the  air-dry 
material  and  this  value  combined  with  the  moisture  loss  on  air 
drying. 

It  may  be  that  the  moisture  loss  on  air  drying  has  not  been 
obtained  but  the  somewhat  simpler  method  has  been  followed  of 
taking  a  special  sample  for  total  moisture.  In  this  case  calcu- 
late the  air  dry  values  to  the  dry  basis  and  multiply  these  values 
by  1  minus  the  total  moisture  found  in  the  " as-received"  sample. 

The  reasons  for  these  various  processes  should  be  clearly 
evident  to  the  student.  A  simple  formula  can  then  be  developed 
as  a  working  convenience.  Note  that  the  general  principle  is 
involved  in  many  other  connections.  For  example,  the  cor- 
rected ash  as  well  as  the  moisture  are  eliminated  in  deriving  the 
values  for  unit  coal  where  the  only  item  wanted  is  the  heat  value 
to  be  transferred  from  the  "wet"  to  the  "unit-coal"  basis. 


CHAPTER  XX 

CALORIMETRY  USING  SODIUM  PEROXIDE 

General  Statement. — The  calorimeter  should  be  placed  on  a 
good,  firm  desk  in  a  room  where  fluctuations  of  temperature  may 
be  avoided.  The  general  arrangement  of  parts  is  shown  in  Fig. 
30.  However,  it  is  better  to  remove  the  can  from  the  instrument 


FIG.  30. — Parr  peroxide  calorimeter,  showing  details  of  construction. 

for  filling  with  water.  The  outside  of  the  can  should  be  dry,  and 
no  water  should  be  allowed  to  spill  over  into  the  air  spaces  of  the 
insulating  vessels. 

Exactly  2  liters  of  water  (preferably  distilled)  are  used,  and 

149 


150  FUEL,  GAS,  WATER  AND  LUBRICATION 

it  should  have  a  temperature  of  2  or  3°F.  below  that  of  the  room. 
The  thermometer,  T,  should  extend  a  little  over  half  way  to  the 
bottom  of  the  can.  The  pulley,  S,  is  connected  by  a  light, 
flexible  cord  with  a  small  electric  or  water  motor.  Stirring  is 
effected  by  the  spring  clips  with  turbine  wings,  TF,  placed  on  the 
bell  body.  The  pulley,  S,  must  be  made  to  revolve  at  a  rather 
brisk  rate.  About  150  r.p.m.,  uniformly  maintained,  will 
insure  a  complete  equalization  of  temperature  throughout  the 
water.  The  pulley  should  turn  to  the  right  or  as  the  hands  of  a 
watch. 

Because  of  the  extended  use  of  the  peroxide  calorimeter  by 
engineers  in  connection  with  the  checking  of  coal  deliveries,  etc., 
these  instruments  are  ordinarily  supplied  with  thermometers 
graduated  in  degrees  Fahrenheit.  Results  are  thus  given  directly 
in  B.t.u.  In  this  discussion  concerning  the  use  of  the  peroxide 
calorimeter,  therefore,  that  type  of  thermometer  is  assumed  to 
be  the  one  used  unless  otherwise  indicated. 

The  Fuel  Sample. — If  the  amount  of  moisture  in  the  air-dried 
coal  is  less  than  1  or  2  per  cent,  no  drying  in  the  oven  is  neces- 
sary for  the  determination  of  calorific  value.  One-half  gram  of 
air-dried  coal  is  used  and  the  detailed  directions  should  be 
followed  as  given  below. 

Concerning  the  amount  of  moisture  permissible  in  the  fuel 
sample,  it  has  been  indicated1  that  the  temperature  rise  in  the 
apparatus  as  used,  due  to  the  absorption  by  the  chemical, 
Na2O2,  of  1  gram  of  water  is  0.663°C.  In  a  J^-gram  sample 
therefore,  2  per  cent  of  moisture  would  represent  0.01  gram  of 
water  which  if  allowed  to  combine  with  the  Na2O2  and  if  all  the 
heat  generated  by  that  absorption  were  included  in  the  calo- 
rimeter process,  that  amount  of  moisture  would  produce  a  rise  of 
0.01  X  0.663  =  0.0066°C.  This  temperature  rise  would  then 
cause  an  error  of  0.0066  X  3,100  =  20  cal.,  which  will  give  suffi- 
cient reason  for  avoiding  the  use  of  a  coal  with  a  high  percentage 
of  moisture.  The  error  for  2  per  cent  of  moisture  would  be  less 
than  the  calculated  amount,  due  to  dissipation  of  the  heat  of 
absorption  before  the  thermometric  readings  were  taken,  but  the 
possibility  of  an  appreciable  error  is  easily  guarded  against. 

1  Constants  of  the  Parr  calorimeter,  Jour.  Am.  Chem.  Soc.,  vol.  29, 
p.  1616,  1907. 


CALORIMETRY  USING  SODIUM  PEROXIDE 


151 


The  Chemical:  Sodium  Peroxide  JVa202. — It  is  absolutely 
necessary  that  the  chemical  employed  (sodium  peroxide)  be  kept 
free  from  contamination.  It  has  special  avidity  for  moisture,  and 
the  glass  jar  with  lever  fastener,  as  shown  in  Fig.  31,  has  been 
found  best  adapted  as  a  container  for  this  material.  The 
sodium  peroxide  is  furnished  in  small  sealed  tins,  and  the  entire 
contents  of  a  can,  upon  opening,  should  be 
transferred  completely  to  the  jar.  The 
half-pound  tins  will  usually  be  found  the 
most  convenient  size  to  use.  In  any  event, 
the  glass  jar  should  be  of  sufficient  size  to 
permit  of  the  complete  emptying  of  the  con- 
tainer. Commercial  sodium  peroxide  or 
material  that  has  been  much  exposed  to 
the  air  so  that  any  considerable  amount 
of  moisture  has  been  absorbed,  will  give 
variable  and  uncertain  results. 

The  Accelerator :  Potassium  Chlorate, 
KC103. — In  order  to  secure  a  combustion 
that  shall  be  uniformly  complete,  it  has  been 
found  desirable  to  use  an  accelerator  for 
the  purpose  of  increasing  or  intensifying  the 
oxidizing  effect  of  the  sodium  peroxide. 
While  numerous  chemical  mixtures  have 
been  tried,  a  very  extended  experience  has  made  it  evident  that 
potassium  chlorate  is  best  adapted  for  this  purpose.  The  amount 
needed  for  each  charge  is  weighed  out  in  the  same  manner  as  for 
coal.  One  gram  is  the  weight  taken  for  fuel  of  all  types. 

Making  Up  the  Charge. — See  that  the  floating  bottom  is  in 
place  at  the  lower  end  of  the  bell  body  as  shown  in  Fig.  32.  The 
inner  surfaces  should  be  dry  so  that  the  fusion  cup,  when  put  in 
place,  will  be  surrounded  by  an  air  space  with  no  film  of  water 
present.  The  fusion  cup  also  should  be  thoroughly  dry  inside 
before  adding  the  charge.  It  is  well  to  dry  it  over  a  radiator  or 
hot  plate,  though  it  should,  of  course,  be  cooled  for  filling.  Add 
to  the  fusion  cup,  not  assembled,  1  gram  of  accelerator  and  one 
full  measure  of  sodium  peroxide.  In  filling  the  measure  with 
peroxide  it  should  be  tapped  against  the  side  of  the  glass  jar  to 
insure  against  the  formation  of  air  pockets  which  might  prevent 


FIG.    31. — Container 
for  sodium  peroxide. 


152 


FUEL,  GAS,  WATER  AND  LUBRICATION 


the  complete  filling  of  the  measure.  The  measure  holds  approxi- 
mately 14  grams.  The  same  precaution  also  as  to  the  dryness  of 
the  measure  should  be  observed  as  for  the  fusion  cup.  It  should 
be  rinsed  thoroughly  with  tap  water  after  each  using  and  dried 
by  heating  over  a  radiator  or  hot  plate.  If  the  accelerator  is 
lumpy,  it  is  well  to  rub  it  smooth  in  the  bottom  of  the  fusion  cup. 


F 


-J 


FIG.  32.  FIG.  33. 

FIG.  32. — Peroxide  calorimeter  bomb,  showing  details  of  construction. 

FIG.  33. — Bomb  cup  with  temporary  top  (actual  size). 

Close  with  the  temporary  top,  Fig.  33,  and  shake  thoroughly 
until  the  ingredients  are  evenly  mixed.  Add  now  J  gram  of 
coal.  Replace  the  temporary  cap  and  shake  again.  Avoid 
exposing  the  mixture  to  the  air  more  than  is  absolutely  necessary 
owing  to  the  extreme  avidity  of  the  chemical  for  moisture. 
When  mixing  is  complete,  tap  the  cup  lightly  on  the  desk  to 
shake  all  of  the  material  from  the  upper  part  of  the  container, 


CALORIMETRY  USING  SODIUM  PEROXIDE  153 

remove  the  temporary  cap  and  put  in  its  place,  at  once,  the 
regular  cap  with  stem  and  ignition  wire.1  To  attach  the  ignition 
wire,  take  a  single  length  of  fuse  wire  7  cm.  long  from  the  card; 
pass  one  end  through  the  eyelet  of  one  of  the  terminals  so  it  will 
extend  beyond  the  eyelet,  say  1  cm.  Wrap  the  free  wire  around 
the  terminal  at  the  narrow  portion  formed  by  the  notch,  giving 
it  three  turns,  binding  in  the  free  end  and  bending  the  wire 
finally  downward  in  line  with  the  terminal.  Repeat  the  same 
process  with  the  other  end  of  the  wire  in  the  other  terminal. 
Do  not  have  the  fuse  loop  too  long.  It  is  better  if  it  does  not 
extend  too  far  into  the  charge.  It  will  be  noticed  that  the 
charge  fills  the  crucible  at  least  two-thirds  full;  hence,  1  cm. 
extension  of  the  fuse  wire  below  the  central  terminal  will  be 
ample. 

See  that  the  rubber  gasket  is  in  good  shape  and  that  the 
stem  cap  seats  itself  properly.  It  is  to  be  noted  that  the  gasket 
seals  both  the  upper  edge  of  the  crucible  and  also  the  upper  edge 
of  the  bell  body.  Marring  the  edges  or  rims  of  any  of  these 
parts,  therefore,  must  be  carefully  avoided.  Screw  down  the 
cap,  d,  firmly  in  place  by  use  of  the  two  wrenches;  put  on  the 
spring  clips  with  the  stirring  vanes  downward,  leaving  the  small 
holes  near  the  lower  edge  of  the  bell  body  uncovered,  and  assemble 
as  shown  in  Fig.  30.  In  assembling,  add  2  liters  of  distilled 
water  having  a  temperature  1  to  2°F.  below  that  of  the  room  and 
place  the  can  in  its  proper  position  in  the  insulating  chamber. 

Ignition. — The  current  required  for  igniting  the  charge  should 
be  from  2  to  4  amp.,  and  is  most  readily  obtained  by  means  of  a 
rheostat  or  sliding  resistance  coil  placed  in  series  in  an  ordinary 
lighting  circuit  of  110  volts. 

Make  a  number  of  preliminary  tests  by  fastening  a  loop  of 

1  Particular  attention  is  called  to  the  necessity  of  obtaining  an  even  mix- 
ture of  the  ingredients.  If  the  accelerator  (KC1O3)  and  coal  alone  are  used 
a  violently  explosive  mixture  results.  If  the  mixing  is  so  poorly  done  that 
lumps  of  accelerator  and  coal  become  segregated,  a  too  great  disturbance 
during  the  reaction  may  occur.  There  is  no  especial  virtue  in  any  particular 
order  of  adding  the  ingredients.  The  above  method  is  believed  to  most 
surely  promote  evenness  of  distribution.  For  these  reasons  also  the  sodium 
peroxide  should  not  be  granular  but  should  have  the  appearance,  when 
emptied  into  the  glass  container,  of  a  uniform  powder,  which  would  prac- 
tically all  pass  a  20-mesh  sieve. 


154  FUEL,  GAS,  WATER  AND  LUBRICATION 

fuse  wire  to  the  terminals  and  passing  the  current  without 
assembling  the  parts.  In  this  way  the  behavior  of  the  fuse  wire 
can  be  observed.  Make  a  trial  with  varying  resistances.  If 
the  wire  does  not  come  very  quickly  to  incandescence,  decrease  the 
resistance  until  it  melts  in  only  1  or  2  sec.  after  closing  the  circuit. 

Temperature  Readings. — The  thermometer  is  inserted  so  that 
the  lower  end  of  the  bulb  will  be  about  midway  toward  the  bot- 
tom of  the  can.  The  pulley  should  be  allowed  to  revolve  a  few 
minutes  before  reading  the  thermometer,  in  order  to  equalize  the 
temperature  throughout  the  apparatus.  Take  readings  one  min- 
ute apart  for  four  or  five  intervals  before  igniting  the  charge,  and 
continue  the  same  for  9  or  10  min.  subsequent  to  ignition.  The 
first  three  or  four  readings  after  ignition  are  roughly  taken,  but 
after  the  fourth  or  fifth  minute  the  temperature  should  be  nearly 
equalized,  and  the  readings  must  be  carefully  taken  in  order  to 
ascertain  the  exact  maximum  and  to  furnish  the  necessary  data 
for  making  a  correction  for  radiation.  If  the  temperature  of  the 
water  before  ignition  is  1  or  2  degrees  below  that  of  the  room,  the 
temperature  at  the  end  of  the  first  minute  after  ignition  will  be 
something  above  that  of  the  room,  and  radiation  for  that  period 
may  be  considered  as  self-correcting.  Ordinarily,  the  rise  in 
temperature  will  continue  for  about  4  min.  more,  at  which  time 
the  maximum  temperature  will  have  been  reached.  The  radia- 
tion for  this  period  is  found  as  follows :  Read  the  fall  in  tempera- 
ture for  each  minute  for  4  min.  after  the  maximum  has  been 
reached.  The  average  drop  per  minute  represents  the  correction 
to  be  added  to  each  minute  preceding  the  maximum,  except  for 
the  minute  immediately  following  ignition.  The  final  tempera- 
ture thus  corrected  for  radiation,  minus  the  initial  reading  before 
ignition,  represents  the  total  rise  in  temperature  due  to  the 
reaction  in  the  fusion  cup. 

In  reading  the  thermometer  a  suitable  lens  should  be  used,  pref- 
erably mounted  in  a  manner  to  eliminate  errors  of  the  paral- 
lax. Tap  the  thermometer  lightly  before  taking  a  reading  in 
order  to  avoid  irregularities  in  the  surface  of  the  mercury.  It 
should  be  remembered  that  errors  in  reading  the  thermometer  are 
multiplied  many  times  in  the  final  computation.  Equalization 
of  temperatures  should  be  complete  in  about  5  min.  This  will 
always  be  the  case  if,  in  the  process  of  cooling,  water  has  been 


CALORIMETRY  USING  SODIUM  PEROXIDE  155 

drawn  into  the  narrow  air  spaces  surrounding  the  fusion  cup. 
If  by  some  mischance  this  entrance  of  the  water  should  fail  to 
take  place  it  will  be  indicated  by  an  absence  of  water  within  the 
holder  around  the  bottom  and  lower  part  of  the  fusion  cup.  It 
will  be  evident  also  by  a  slow  but  very  evident  rise  of  the  mercury 
over  a  period  of  10  or  15  min.,  due  to  the  slow  conductance  of  the 
heat  through  the  limited  areas  of  metal  contact  between  the 
holder  and  the  cup. 

Calculations. — From  the  total  rise  in  temperature,  corrected 
for  radiation  as  above  indicated,  subtract  the  correction  factors 
for  the  heat  due  to  the  chemical,  fuse- wire,  etc.,  as  indicated 
under  "  Correction  Factors"  below,  and  multiply  the  remainder  by 
3,100.  The  product  will  be  the  number  of  British  thermal  units 
per  pound  of  coal  (see  notes  (a),  (6)  and  (c)  below). 

It  is  to  be  noted  that  the  heat  value  as  derived,  refers  to  the 
coal  in  the  form  in  which  it  is  weighed  out  for  making  the  deter- 
mination. That  is  to  say,  if  a  coal  having  5  per  cent  of  moisture 
is  taken  and  \  gram  of  the  same  weighed  out  and  dried  in  the 
oven  at  212°  for  1  hr.,  then  burned  in  the  calorimeter,  the  result 
obtained  refers  to  the  coal  on  the  basis  of  5  per  cent  of  moisture 
and  not  to  the  coal  as  in  the  oven-dry  state. 

To  calculate  values  to  "dry  coal,"  divide  the  number  by  100 
minus  the  per  cent  of  moisture  present.  Thus,  a  coal  having 
5  per  cent  moisture  and  indicating  11,000  B.t.u.  would  have 
11,000  •*-  .95  =  11,579  B.t.u.  on  the  "dry-coal"  basis. 

Note  (a),  Correction  Factors. — The  method  for  obtaining  the 
correction  for  radiation  has  already  been  described  under  "  Tem- 
perature Readings."  The  other  correction  components  are 
listed  for  convenient  reference  as  follows: 

Electric  fuse  wire  equals 0 . 003°C.  or  0 . 005°F. 

Per  cent  ash  is  multiplied  by 0 . 0025°C.  or  0 . 005°F. 

Per  cent  sulphur  is  multiplied  by 0 . 005°C.  or  0 . 010°F. 

1  gram  accelerator  equals 0. 150°C.  or  0.270°F. 

Hydration  factors: 

For  all  bituminous  coals 0 . 040°C.  or  0 . 070°F. 

For  black  lignites 0 . 056°C.  or  0 . 100°F. 

Note  (b). — The  factor  3,100  is  deduced  as  follows:  The  water 
used  plus  the  water  equivalent  of  the  metal  in  the  instrument 
amounts  to  2,123.3  grams.  In  the  reaction  73  per  cent  of  the 


156  FUEL,  GAS,  WATER  AND  LUBRICATION 

heat  is  due  to  combustion  of  the  coal  and  27  per  cent  is  due  to  the 
heat  of  combination  of  C02  and  H20  with  the  chemical.  If 
now  J  gram  of  coal  causes  2,123.3  grams  of  water  to  rise  r  degrees, 
and  if  only  73  per  cent  of  this  is  due  to  combustion,  then  0.73  X 
2,123.3  X  2  X  r  =  rise  in  temperature  which  would  result  from 
combustion  of  an  equal  weight  (2,123.3  grams)  of  coal.  0.73  X 
2,123.3  X  2  =  3,100.00.  The  factor  2  is  used  instead  of  the 
divisor  0.5,  the  weight  of  coal  taken. 

Note  (c). — The  hydration  factor  represents  the  heat  of  com- 
bination between  the  chemical  and  water  of  decomposition  and 
is  a  different  item  from  the  water  of  combustion  which  forms 
from  the  burning  of  the  available  hydrogen.  The  oxygen  com- 
pounds of  coal  are  liberated  as  H20  or  C02  and  produce  a  small 
increment  of  heat  upon  uniting  with  the  Na202  which  can  not  be 
credited  to  the  true  heat  of  combustion.  Hence,  correction  is 
applied  for  such  compounds.  This  feature  may  also  be  well 
illustrated  in  the  case  of  benzoic  acid  whose  formula  (CyHeCW 
shows  the  presence  of  an  equivalent  of  2H20,  the  heat  for  the 
absorption  of  which  should  be  corrected  for  and  not  counted  as 
a  part  of  the  true  heat  of  combustion. 

To  Dismantle. — Remove  the  thermometer,  pulley  and  cover; 
then  take  out  the  can  and  contents  entire,  so  that  the  lifting  out 
of  the  cartridge  will  not  drip  water  into  the  dry  parts  of  the 
instrument.  Remove  the  fusion  cup  and  place  it  on  its  side  in 
the  bottom  of  a  beaker  and  cover  with  hot  water.  After  the 
fused  material  has  dissolved,  remove  the  cup  and  rinse  thoroughly 
with  hot  water.  Wash  the  face  of  the  cap  and  electric  terminals 
thoroughly.  For  this  purpose  a  jet  of  hot  water  or  submerging 
in  boiling  water  is  advisable,  as  the  metal  is  thus  left  clean  and  hot, 
the  latter  facilitating  the  drying  out  of  the  parts.  Place  the 
parts  on  a  radiator  or  near  a  hot  plate  to  insure  thorough  drying. 

Anthracites  and  Coke. — In  the  case  of  anthracites  and  coke, 
it  is  well  to  use  0.2  grams  of  benzoic  acid  along  with  the  1  gram 
of  accelerator  and  J  gram  of  fuel.  This  substance  facilitates 
ignition  as  well  as  the  ultimate  combustion.  The  heat  resulting 
from  the  combustion  of  this  extra  0.2  gram  of  benzoic  acid, 
which  is  to  be  corrected  for  along  with  the  other  correction  com- 
ponents, is  1.550°F.  For  hard  fuels  of  this  type  it  will  be 
found  of  advantage  to  grind  the  sample  to  pass  a  100  mesh  sieve. 


CALORIMETRY  USING  SODIUM  PEROXIDE  157 

For  Petroleum  Oils. — The  amount  of  oil  used  for  a  charge 
should  not  exceed  about  0.3  gram;  from  0.20  to  0.30  gram  giving 
the  proper  combustion.  The  weight  of  oil  is  best  obtained  by 
means  of  a  small  light  15  cc.  weighing  flask  provided  with  perfo- 
rated cork  and  dropping  tube  with  common  rubber  bulb-cap. 
Weigh  the  flask  and  contents,  and  by  means  of  the  dropping  tube 
discharge  20  to  30  drops  of  oil  and  re-weigh,  thus  obtaining  the 
weight  of  oil  taken  by  difference.  Determine,  by  experiment, 
the  height  in  the  dropping  tube  required  for  the  approximate 
amount  of  oil  desired  so  as  to  avoid  trial  weighings. 

One  gram  of  accelerator  and  one  full  measure  of  chemical 
(sodium  peroxide)  are  first  added  and  thoroughly  shaken  as 
already  indicated.  Also,  to  facilitate  the  ignition  of  all  oils  and 
at  the  same  time  promote  the  ultimate  combustion,  it  is  recom- 
mended that  a  small  amount  (0.2  gram)  of  behzoic  acid  be  used 
as  described  under  "  Anthracites  and  Coke."  Add  the  oil  and 
benzoic  acid  last  and  mix  thoroughly  by  shaking  as  already  indi- 
cated and  complete  the  process  exactly  as  for  coal. 

Note  that  thorough  mixing  by  shaking  is  not  easily  accom- 
plished in  the  case  of  thick  viscous  oils.  After  thorough  shaking 
of  the  accelerator,  chemical  and  benzoic  acid,  the  thick  oil  should 
be  added,  a  few  drops  at  a  time  and  stirred  with  a  nichrome  wire 
till  there  is  no  more  tendency  of  the  oil  and  chemical  to  segregate 
into  lumps.  After  closing  the  bomb,  a  final  shaking  will  insure 
an  even  distribution  of  the  oil  throughout  the  charge. 

Compute  by  means  of  the  formula  as  follows : 

Correcting  as  under  coals  for  radiation,  accelerator,  benzoic 
acid  and  fuse-wire,  and  letting  r  represent  the  rise  in  temperature; 
then 

r  X  0.73  X  2,123.3       ^  ,  ,     ,    .. 

— ^rr—f — n —  =  B.t.u.  per  pound  of  oil. 
weight  of  oil 

Gasoline,  Etc. — For  gasoline,  benzene  and  other  very  volatile 
hydrocarbons  the  difficulty  of  securing  an  accurate  weight  of  the 
material  taken  is  met  by  the  following  procedure:  Draw  out 
an  ordinary  soft  glass  tube  into  a  capillary  about  1  mm.  in 
diameter.  By  softening  the  end  it  may  be  blown  into  a  small 
thin  walled  bulb  as  shown  in  Fig.  34.  After  a  little  practice  it  is 
not  difficult  to  blow  such  bulbs  to  weigh  less  than  0.2  gram. 
They  are  used  as  follows:  Weigh  the  bulb  carefully,  then  by  dip- 


158 


FUEL,  GAS,  WATER  AND  LUBRICATION 


ping  the  capillary  end  into  the  liquid  and  alternately  warming 
gently  and  cooling  the  bulb  a  quantity  of  the  liquid  may  be  made 
to  flow  up  into  it.  When  about  0.2  gram  is  obtained,  seal  the 
tip  of  the  capillary  in  the  flame  and  weigh  accurately.  Add  the 
accelerator  to  the  fusion  cup  in  the  usual  manner  reducing  any 
lumps  to  a  fine  powder.  Add  also  0.2  gram  carefully  weighed 
standard  benzoic  acid  and  the  bulb  containing  the  liquid  fuel, 
then  over  all,  the  measure  of  sodium  peroxide.  Press  a  glass 


FIG.  34. — Glass  bulbs,  used  as  containers  for  volatile  liquids. 

rod  down  through  the  chemical  above  the  bulb  just  sufficient 
to  break  it.  Remove  the  rod  which  should  be  freed  from  adher- 
ing particles  by  cleaning  it  in  the  upper  part  of  the  sodium  per- 
oxide as  yet  unmixed  with  any  of  the  other  ingredients.  Put  in 
place  as  quickly  as  possible  the  ignition  top  with  fuse  wire 
attached  and  clamp  firmly  in  place  by  means  of  the  screw  cap. 
Shake  very  thoroughly  to  insure  complete  mixing  of  the  charge. 
Tap  lightly  on  the  desk  to  bring  all  of  the  material  together  and 
assemble  for  the  regular  procedure.  In  calculating,  a  correction 
is  necessary,  in  addition  to  those  normally  observed,  on  account 
of  the  heat  of  fusion  due  to  the  glass  present.  This  amounts  to 
0.03°F.  for  each  0.1  gram  of  glass  used  in  the  bulb.  This  should 
be  subtracted  along  with  the  correction  for  accelerator  benzoic 


CALORIMETRY  USING  SODIUM  PEROXIDE  159 

acid  and  fuse  wire.  The  corrected  rise,  r,  is  then  used  in  the 
formula  as  above  given  for  petroleums. 

Standardization. — A  number  of  methods  for  the  standardiza- 
tion of  the  peroxide  calorimeter  may  be  used,  (a)  By  calculating 
the  water  equivalent  for  the  metal  a  very  satisfactory  factor  is 
obtained  which  serves  as  a  constant  in  calculating  the  heat 
values.  The  accuracy  of  this  method  in  connection  with  the 
peroxide  type  of  instrument  is  due  to  the  relatively  small  amount 
of  metal  employed  in  its  construction,  together  with  the  fact 
that  all  metal  parts  are  standardized  as  to  weight  in  the  process 
of  manufacture.  The  total  weight  of  metal  not  including  the 
pulley  and  insulated  part  of  the  stem  is  approximately  1,370 
grams.  Applying  a  specific  heat  value  of  0.090  gives  a  water 
equivalent  for  the  metal  of  123.3  or  a  total  water  equivalent 
\4alue  of  2,123.3  which  is  the  basis  for  determining  the  constant 
of  3,100,  as  already  shown  under  "  Calculations."  (6)  A  standard 
coal  for  which  the  heat  value  has  been  accurately  derived  by  an 
oxygen-bomb  apparatus  of  the  Mahler  type.  This  requires  that 
the  Mahler  value  be  recently  determined  owing  to  the  change 
in  the  apparent  heat  value  of  coal  samples  upon  standing.  It 
has  the  advantage,  however,  of  checking  the  peroxide  instrument 
with  respect  to  the  correction  factors  used  for  ash,  sulphur  and 
water  of  composition  or  "hydration."  (c)  By  combustion  of 
standard  material  as  sugar  or  benzoic  acid.  The  latter  is  usually 
employed.  It  has  the  advantage  over  the  first  method,  (a),  in 
that,  it  furnishes  a  test  for  the  behavior  of  the  thermometer,  but 
with  a  thermometer  of  proper  grade  the  variations  on  that 
account  are  due  to  uncertain  or  erroneous  reading  of  temperatures 
which  no  method  of  standardization  can  correct. 

The  charge  consists  of  f  gram  of  benzoic  acid,  (CrEeC^), 
carefully  weighed  out  and  added  to  the  fusion  cup  which  already 
contains  the  accelerator  and  sodium  peroxide  thoroughly  mixed 
exactly  as  in  the  procedure  for  coal.  After  adding  the  benzoic 
acid  the  cup  is  again  thoroughly  shaken  to  insure  complete 
mixing  of  the  entire  charge. 

After  combustion  in  the  ordinary  manner  and  correcting  the 
temperature  rise  for  radiation,  the  accompanying  factors  are 
noted  as  follows: 


160  FUEL,  GAS,  WATER  AND  LUBRICATION 

COMPONENT  FACTORS  FOR  BENZOIC  ACID 
Fuse  wire  ..........................   0.003°C.  or  0.005°F. 

Accelerator  .........................   0.  150°C.  or  0.270°F. 

Hydration  ..........................   0.100°C.  or  0.180°F. 

Total  corrections  ..................   0.253°C.  or  0.455°F. 

Heat  of  reaction  .....................   2  .  040°C.  or  3  .  670°F. 

Total  rise  ........................   2.293°C.  or  4.125°F. 

From  the  above  it  is  seen  that  the  total  rise  in  temperature  as 
corrected  for  radiation,  after  having  the  normal  corrections 
applied  for  fuse,  accelerator  and  hydration,  should  have  a 
remainder,  representing  the  true  heat  of  combustion,  of  2.040°C. 
or  3.670°F.,  since  this  value  multiplied  by  the  constant  3,100  gives 
6,320  Cal.  or  11,376  B.t.u.,  the  accepted  value  for  benzoic  acid. 

If  after  several  check  combustions,  the  values  indicated  by  the 
instrument  show  a  consistent  variation,  the  average  difference 
in  heat  rise  should  be  added  if  +  and  subtracted  if  —  from  the 
true  heat  of  combustion  and  the  remainder  used  as  a  divisor  for 
the  accepted  value  thus  :  with  an  excess  indication  of  0.02°F.  we 
would  have: 


3.690   " 

That  is,  the  constant  for  the  instrument  is  3,083  instead  of 
11,376 

"  =  3>100- 


CHAPTER  XXI 

CALORIMETRY  USING  THE  OXYGEN  BOMB 

General  Statement. — In  the  Mahler  or  Berthelot  type  of 
instrument,  the  fuel  for  combustion  is  held  in  a  tray  supported 


u  u 

FIG.  35. — Cross  section  of  Parr  oxygen  bomb. 

within  a  chamber  capable  of  receiving  oxygen  under  a   pressure 
of  25  to  30  atmospheres.     Figure  35  represents  such  a  bomb,  the 
essential  parts  of  which  are  the  cover,  C,  held  in  place  by  the 
11  161 


162 


FUEL,  GAS,  WATER  AND  LUBRICATION 


screw  clamp,  A,  the  supporting  wires,  D,  for  the  fuel  tray,  H, 
which  also  are  the  terminals  for  conducting  the  electric  current 
through  the  fine  fuse  wire.  The  assembling  of  the  bomb  in  the 


FIG.  36. — Parr  oxygen  bomb  calorimeter,  showing  details  of  construction. 

calorimeter  proper  is  shown  in  Fig.  36.  The  bomb  is  placed  a 
little  to  one  side  of  the  center  of  an  oval  can  thus  leaving  space 
at  one  axis  of  the  oval  for  a  stirrer,  S,  and  at  the  other  for  a 
thermometer,  T.  Protection  from  heat  interchanges  with  the 


CALORIMETRY  USING  THE  OXYGEN  BOMB  163 

surrounding  air  is  provided  by  walls  of  indurated  fiber  with  an 
air  space  between  and  this  arrangement  is  continuous  for  sides, 
bottom  and  top.  Another  method  of  insulation  by  circulation 
of  water  through  the  jacketing  spaces  is  also  to  be  noted.  The 
fuse  wire  is  No.  34,  Brown  &  Sharpe  gage,  and  is  usually  of 
pure  iron  though  on  some  accounts  a  wire  more  resistant  to 
oxidation  is  desirable.  A  current  of  low  voltage  10  to  15  volts 
is  to  be  preferred  so  that  arcing  within  the  calorimeter  may  be 
avoided. 

The  capsule  should  be  immune  to  chemical  action  and  if 
of  sufficient  size  the  necessity  of  compressing  the  fuel  into  a 
tablet  is  obviated.  Trays  approximately  25  mm.  in  diameter  by 
12.5  mm.  deep  should  be  used. 

Oxygen  bomb  calorimeters  of  the  Mahler  or  Berthelot  type, 
naturally,  by  inheritance  or  custom,  ordinarily  are  equipped  with 
thermometers  graduated  in  degrees  Centigrade .  Unless  otherwise 
indicated,  therefore,  references  to  temperature  readings  in 
connection  with  instruments  of  this  type  are  understood  to  be  on 
the  Centigrade  scale. 

Heat  Values  by  Oxygen  Bomb  Calorimeter. — Figure  35  shows 
the  arrangement  of  the  parts  of  the  bomb  when  ready  for  placing 
in  the  calorimeter.  When  the  calorimeter  is  dismantled  the 
double  cover  to  the  insulating  chamber  should  be  supported  on  a 
ring-stand  or  similar  device  as  shown  in  the  cut,  Fig.  37.  This 
affords  a  convenient  method  of  handling  the  stirring  device  and 
insures  greater  safety  for  the  thermometer. 

When  the  bomb  is  opened  and  made  ready  to  receive  the 
charge  of  fuel,  the  cap  is  most  conveniently  held  on  a  ring-stand. 
Thus  supported,  the  fuel  capsule  and  fuse  wire  are  readily 
adj usted .  For  coal  approximately  one  gram  of  the  air-dry  sample, 
ground  to  pass  a  60-mesh  sieve,  is  accurately  weighed  in  the 
capsule,  //,  Fig.  35.  Attach  the  ignition  wire  to  the  terminals 
by  passing  one  end  through  the  eyelet  of  one  of  the  terminals  so 
it  will  extend  beyond  the  eyelet  about  1  cm.  Wrap  the  free  wire 
around  the  terminal  at  the  narrow  portion  formed  by  the  notch, 
giving  it  three  turns,  binding  in  the  free  end  and  bending  the 
wire  finally  downward  in  line  with  the  terminal.  Repeat  the 
same  process  with  the  other  end  of  the  wire.  The  fuse  wire 
should  be  about  7  cm.  long.  That  part  of  the  wire  between  the 


164 


FUEL,  GAS,  WATER  AND  LUBRICATION 


terminals  should  be  bent  into  a  somewhat  narrow  U-shaped  loop 
so  that  the  fuse  wire  will  not  touch  the  sides  of  the  capsule,  Fig. 
35.  Adjust  the  wire  so  that  the  lower  part  of  the  fuse  loop 
will  just  touch  the  surface  of  the  coal.  In  using  sugar  for 


FIG.  37. — Oxygen  bomb  calorimeter,  dismantled. 

standardizing  purposes  it  is  well  to  give  the  wire  a  number  of 
short  turns  in  such  a  manner  that  the  spiral  will  come  in  contact 
with  the  sugar,  which  is  difficult  to  ignite  with  the  wire  in  a 
simple  loop.  Benzoic  acid  or  naphthalene  are  easy  to  ignite 
and  do  not  need  the  extra  looping  of  the  wire.  In  the  case  of 


CALORIMETRY  USING  THE  OXYGEN  BOMB  165 

naphthalene,  to  insure  against  loss  of  the  charge  upon  igniting,  it 
is  well  to  heat  approximately  1  gram  in  the  capsule  to  the  point 
of  incipient  fusion  and  then  obtain  the  accurate  weight.  The 
cake-like  mass  will  readily  ignite  if  the  wire  loop  simply  touches 
the  surface.  Loss  by  volatilization  or  spurting  is  thus  avoided. 
In  the  case  of  coal  or  standard  material  the  amount  to  be  taken 
is  a  matter  of  choice.  An  exact  gram  simplifies  slightly  the 
calculations,  but  is  apt  to  prolong  unduly  the  weighing  process. 
A  small  amount  of  water,  0.5  to  1.0  gram  is  added  to  the  bomb 


FIG.  38. — Method  of  filling  oxygen  bomb  with  oxygen. 

which  is  placed  in  the  octagon  holder  for  receiving  the  cover  with 
the  fuel  and  capsule  in  place.  In  turning  down  the  cap  upon  the 
cover  apply  the  large  wrench  using  good  firm  pressure,  though 
only  moderate  force  is  necessary  for  securing  a  perfect  seal  at 
the  rubber  gasket. 

For  filling  with  oxygen,  connection  is  made  with  the  flexible 
copper  tubing  (see  Fig.  38)  and  oxygen  is  admitted  until  a 
pressure  of  25  to  30  atmospheres  is  indicated.  In  admitting  the 
oxygen  the  needle  valve  next  to  the  pressure  gage  is  opened 
slightly  to  avoid  a  sudden  rush  of  gas.  After  a  sufficient  amount 
has  been  admitted,  close  the  needle  valve  and  open  the  pet  cock 
below  the  gage  in  order  to  release  the  oxygen  under  pressure  in 


166  FUEL,  GAS,  WATER  AND  LUBRICATION 

the  tube  and  connections.  The  check  valve,  V,  Fig.  35,  auto- 
matically closes  and  retains  the  oxygen  at  the  desired  pressure. 

Transfer  the  bomb  carefully,  without  jarring,  to  the  oval  can 
which  has  been  placed  in  position  in  the  calorimeter.  The  long 
axis  of  the  oval  should  be  in  line  with  the  operator,  that  is,  at 
right  angles  to  the  work  desk.  The  pointer,  Fig.  37,  and  a  notch 
in  the  can  directly  opposite,  serve  as  guides  for  correctly  locating 
the  vessel.  The  circular  elevation  in  the  bottom  which  directs  the 
locating  of  the  bomb  should  be  toward  the  operator.  Turn  the 
bomb  so  that  one  of  the  faces  of  the  octagon,  rather  than  an 
angle,  will  be  toward  the  operator,  thus  giving  more  room  for  the 
thermometer.  Make  the  connection  with  the  electric  terminal, 
and  add  2,000  grams  of  water,  preferably  distilled.  The  tempera- 
ture of  the  water  should  be  1  or  2°C.  below  that  of  the  room. 

In  placing  the  cover  on  the  calorimeter  have  the  thermometer 
toward  the  operator.  This  will  bring  the  pulley  with  turbine 
stirrer  at  the  back  of  the  instrument.  Bring  the  cover  to  place 
carefully  so  as  to  avoid  striking  the  thermometer  against  the 
metal  parts  (see  Fig.  36).  Seat  the  spring  clips  for  holding  the 
cover  firmly  in  place  and  connect  the  pulley  with  the  motor. 
The  motor  is  adjusted  so  as  to  give  the  turbine  pulley  a  speed  of 
about  150  r.p.m.  turning  to  the  right  or  clockwise.  A  uniform 
speed  throughout  a  determination  is  desirable. 

By  use  of  the  telescopic  lens,  readings  of  the  thermometer  for 
the  preliminary  period  are  taken  at  1  min.  intervals  for  5  min. 
At  the  fifth  reading  close  the  electric  circuit  for  a  second  or  not 
to  exceed  2  sec.  Ignition  of  the  sample  should  be  indicated  by  a 
rise  of  the  mercury,  which  becomes  rapid  after  20  or  30  sec.  The 
combustion  period  extends  over  5  or  6  min.  and  terminates  when 
the  maximum  temperature  has  been  reached,  or  when  the  rate 
of  change  has  become  uniform.  The  final  period  follows  the 
combustion  period.  Readings  are  taken  at  minute  intervals  for 
5  min.  The  temperature  readings  for  these  periods  furnish 
the  basis  for  determining  the  temperature  changes  due  to  radia- 
tion as  follows:1 

1  See  report  of  Committee  on  Methods  of  Coal  Analysis,  Jour.  Ind.  and 
Eng.  Chem.,  vol.  5,  p.  517,  1913. 

Also,  U.  S.  Bureau  of  Standards,  Circular  11.     Detailed  discussion  in 
Part  I,  p.  40,  should  also  be  consulted. 


CALORIMETRY  USING  THE  OXYGEN  BOMB  167 

The  following  notations  should  be  made. 

1.  The  rate  of  rise  (r)  for  the  preliminary  period  in  degrees  per  minute. 

2.  The  time  (a),  at  which  the  last  reading  of  the  preliminary  period  is 
made,  immediately  before  firing. 

3.  The  time  (6)  when  the  rise  of  temperature  has  reached  six-tenths  of 
its  total  amount.     This  point  can  generally  be  determined  by  adding  to 
the]  temperature  reading  at  the  time  of  firing  60  per  cent  of  the  expected 
temperature  rise  and  noting  the  time  (b)  when  this  point  is  reached.     If  the 
approximate  temperature  rise  is  not  known,  six-tenths  of  the  total  rise  as 
subsequently  developed,  when  added  to  the  temperature  reading  at  (a), 
will  indicate  the  time  (6)  by  interpolating  readings,  which  should  be  taken 
at  15  sec.  intervals  for  2  min.  after  firing. 

4.  The  time  (c)  when  the  maximum  temperature  has  been  reached,  or 
when  the  rate  of  change  has  become  uniform,  usually  about  5  min.  after  firing. 

5.  The  rate  of  change  (r2)  for  the  final  period  in  degrees  per  minute. 

After  combustion  dismantle  the  calorimeter  by  removing  the 
cover  of  the  insulating  fiber  jacket  which  should  be  placed  in  a 
suitable  holder  to  guard  against  breaking  the  thermometer, 
Fig.  37.  Transfer  the  bomb  to  the  octagon  holder  in  the  bench 
(see  Fig.  38)  and  release  the  oxygen  from  the  bomb  by  pressing 
down  upon  the  valve  V.  Do  not  try  to  remove  the  screw  cap, 
A,  until  after  the  gas  pressure  has  been  released.  Upon  opening 
the  bomb  if  any  unburned  carbon  is  found  the  experiment  should 
be  rejected. 

Corrections. — (1)  Apply  the  corrections  as  indicated  on  the 
thermometer  certificate  for  the  initial  (a)  and  final  (c)  readings. 

Determine  the  corrections  for  radiation  as  follows: 

Multiply  the  rate  (r)  by  the  time  (b  —  a)  in  minutes  and  tenths 
of  a  minute  and  add  the  product  to  the  corrected  temperature 
reading  at  time  (a),  or  subtract  it  if  the  temperature  was  falling 
at  time  (a). 

Multiply  the  rate  (r2)  by  the  time  (c  —  6)  and  add  (or  sub- 
tract if  the  temperature  was  rising  during  the  final  period)  the 
product  to  the  corrected  temperature  reading  at  time  (c). 

The  difference  of  the  two  readings  thus  modified  to  account 
for  thermometer  scale  and  radiation  corrections  gives  the  total 
rise  of  temperature. 

2.  Multiply  the  total  rise  thus  found  by  the  water  equivalent 
of  the  calorimeter,  the  product  giving  the  total  amount  of  heat 
liberated.  If  the  thermometer  readings  were  in  Fahrenheit 


168  FUEL,  GAS,  WATER  AND  LUBRICATION 

degrees  the  product  gives  the  heat  value  in  B.t.u.  Unless 
otherwise  stated  the  readings  with  the  oxygen  bomb  instru- 
ment are  considered  as  Centigrade  and  the  ultimate  values  are 
in  calories. 

3.  The  total  heat  as  obtained  under  (2),  after  calculating  to 
calories,  is  to  be  further  corrected  on  account  of  the  formation  of 
nitric  and  sulphuric  acids  in  the  reaction.  Correction  for  these 
acids  however  is  most  conveniently  brought  to  the  basis  of  the 
heat  units  involved  as  follows:  Wash  the  bomb  thoroughly  with 
hot  distilled  water  and  titrate  the  washings  with  a  standard  solution 
of  sodium  carbonate.  Make  up  the  sodium  carbonate  solution 
by  dissolving  3.658  grams  of  chemically  pure  Na2C03  in  one 
liter  of  distilled  water.  Each  cubic  centimeter  of  the  sodium  car- 
bonate solution  represents  an  amount  of  nitric  acid  producing 
1  cal.  in  the  reactions  involved. 

The  additional  correction  for  sulphuric  acid  as  shown  on  page 
44,  Part  I,  requires  that  a  determination  of  sulphur  be  at  hand. 
It  can  be  made  from  the  washings  after  titrating  for  the  acids 
either  by  the  gravimetric  or  photometric  method.  Multiply 
the  per  cent  of  sulphur  present  by  13.  The  product  equals  the 
number  of  calories  to  be  combined  with  the  number  found  by 
titration.  Add  also  the  correction  indicated  for  the  fuse  wire 
which  will  equal  substantially  2.8  cal.  for  each  centimeter  burned. 
The  sum  represents  the  total  correction  in  calories  to  be  sub- 
tracted from  the  amount  obtained  from  the  total  corrected 
temperature  under  (6).1 

Finally,  note  that  the  total  indicated  heat  as  corrected  for 
nitric  acid,  sulphuric  acid,  and  fuse  wire,  refers  to  a  quantity  of 
fuel  represented  by  the  weight  of  the  charge  taken.  If  this 
weight  were  exactly  1  gram  no  further  computation  is  necessary. 
If  the  weight  taken  varied  from  an  even  gram,  the  indicated 
calories  as  above  derived  must  be  divided  by  the  weight  of  fuel 
taken. 

Note  especially,  also,  that  if  a  thermometer  with  the  Fahren- 
heit scale  is  used  the  values  are  in  B.t.u.  but  the  corrections  for 
acid  and  fuse  wire  must  be  changed  to  correspond.  In  this  case 
it  will  be  simpler  to  make  up  the  standard  Na2CO3  solution  by 
using  2.032  grams  per  liter  and  increasing  the  titration  factor  by 

1  For  further  discussion  of  corrections  see  Part  I,  Chap.  VI. 


CALORIMETRY  USING  THE  OXYGEN  BOMB  169 

23  times  the  per  cent  of  sulphur.  The  wire  factor  also  should  be 
taken  as  5  units  per  centimeter  of  length.  Calculations  from 
these  values  will,  then,  all  be  in  B.t.u.  which  are  subtracted  from 
the  total  indicated  B.t.u.  to  cover  the  corrections  involved. 

Standardization. — To  standardize  the  instrument,  make  a 
combustion  using  a  standard  substance  of  known  heat  value,  as 
pure  benzoic  acid.  Add  to  the  accepted  heat  value  of  the 
quantity  taken,  say  1  gram,  the  heat  due  to  the  combustion  of 
the  wire  and  the  nitric  acid  formed.  Divide  the  heat  value  thus 
represented  by  the  temperature  rise,  corrected  in  the  usual 
manner.  The  quotient  represents  the  total  water  equivalent 
made  up  to  the  actual  grams  of  water  employed,  2,000  plus  the 
equivalent  in  water  of  the  metal  parts,  etc.  of  the  apparatus. 
The  substances  most  commonly  used  with  the  values  recognized 
by  the  U.  S.  Bureau  of  Standards  are: 

Benzoic  acid 6 , 320  cal.  per  gram 

Naphthalene 9,622  cal.  per  gram 

Cane  sugar 3 , 949  cal.  per  gram 

Variations  from  these  values  due  to  impurities  may  still  permit 
of  the  substances  being  used  provided  the  values  themselves 
have  been  carefully  determined  under  properly  standardized 
conditions. 

Adiabatic  Conditions. — In  the  case  of  an  adiabatic  calo- 
rimeter, Fig.  13,  assuming  that  perfect  adiabatic  conditions  are 
maintained,  the  matter  of  obtaining  a  correct  temperature 
reading  is  greatly  simplified. 

Before  starting  the  combustion  the  jacketing  water  should  be 
brought  to  exact  equilibrium  with  the  water  surrounding  the 
oxygen  bomb.  This  should  be  maintained  for  2  or  3  min.  to 
insure  that  exact  equilibrium  conditions  have  been  established. 
After  ignition  the  outer  system  should  be  advanced  in  tempera- 
ture with  the  inner  unit  until  equilibrium  conditions  are  again 
established.  During  this  period  of  active  advance  the  two 
thermometers  may  momentarily  be  separated  slightly  as  to 
their  temperature  indications  but  such  variations  would  not 
introduce  measurable  amounts  of  radiation  loss  or  gain  unless 
continued  over  a  considerable  length  of  time.  Moreover,  it 
should  not  be  difficult  to  confine  such  thermometer  variations 


170  FUEL,  GAS,  WATER  AND  LUBRICATION 

within  a  range  of  less  than  one-tenth  of  a  degree.  As  the  final 
stage  is  approached,  these  variations  may  be  reduced  to  the 
point  of  practical  elimination. 

The  corrections  and  calculations  therefore  would  be: 

(a)  Apply  stem  corrections  for  the  thermometer  at  the  initial  and  final 
readings. 

(6)  Multiply  the  rise  by  the  water  equivalent  of  the  instrument. 

(c)  Subtract  the  calories  due  to  the  formation  of  HNO3,  H2SO4  and  fuse 
wire. 

(d)  Divide  by  the  weight  of  the  sample  taken. 


CHAPTER  XXII 

SULPHUR  DETERMINATIONS 

General  Statement. — In  the  ordinary  proximate  analysis,  the 
sulphur  content  of  coal  is  distributed  between  the  volatile  matter 
and  the  coke.  This  distribution  follows  no  definite  plan,  though 
very  frequently  the  sulphur  divides  itself  about  equally.  Since 
the  sulphur  is  thus  included  in  the  factors  obtained,  the  results 
total  100  per  cent.  The  factor  for  sulphur  therefore  is  inde- 
pendent of  the  other  components  and  to  avoid  confusion  should 
be  reported  on  a  separate  line  and  not  listed  with  the  constituents 
determined  by  proximate  analysis. 

The  sulphur  content  is  primarily  of  interest  to  the  analyst 
because  of  the  necessity  of  knowing  this  factor  in  making  the 
necessary  calorimetric  corrections  for  both  the  peroxide  and  the 
oxygen  bombs.  The  user  of  the  coal  in  combustion  processes 
looks  upon  the  sulphur  percentage  as  a  fairly  reliable  index  of  the 
tendency  of  the  coal  toward  clinker  formation.  The  gas  and 
coke  maker  prescribes  a  low  percentage  as  a  maximum  quantity 
beyond  which  the  coal  is  unsuited  for  this  purpose.  In  all  these 
cases  therefore  the  total  sulphur  content  is  required.  The 
methods  of  analysis  are  mainly  directed  therefore  to  this  end. 
For  some  purposes,  however,  the  ratio  of  distribution  as  between 
the  mineral  or  pyritic  sulphur  and  that  which  is  in  organic  com- 
bination is  desired  and  brief  reference  to  such  determinations  are 
included. 

Total  Sulphur. — (a)  The  washings  from  an  oxygen  bomb 
calorimeter  give  values  which  are  sufficiently  accurate  for  the 
corrections  needed  in  the  use  of  that  instrument.  The  washing 
should  be  thorough  and  hot  water  is  preferred.  Heat  the  wash- 
ings to  boiling  with  a  few  cubic  centimeters  of  dilute  (1:1)  HC1  to 
which  a  little  bromine  water  has  been  added.  The  ash  and  insol- 
uble sulphates  remaining  should  be  filtered  off  and  also  washed 
with  hot  water.  Make  neutral  to  methyl  orange  by  means  of 
sodium  hydroxide  or  carbonate,  acidify  with  1  cc.  of  approxi- 
mately normal  HC1  and  heat  to  boiling.  The  bulk  of  the  solu- 

171 


172 


FUEL,  GAS,  WATER  AND  LUBRICATION 


tion  should  not  exceed  about  200  cc.  Add  slowly  from  a  pipette, 
with  constant  stirring,  lOcc.  of  a  10  per  cent  solution  of  barium 
chloride  (BaCl2.2H2O).  Continue  boiling  for  15  min.  and  allow 
to  stand  for  2  hr.  or  over  night.  Decant  the  supernatant  liquid, 
filter  through  an  ashless  filter  and  wash  thoroughly.  Transfer 
the  wet  filter  to  a  weighed  crucible  and  smoke  off  the  paper 
carefully  to  avoid  spattering  and  so  slowly  that  the  filter  paper 
does  not  burn  with  a  flame.  Finally  heat  to  900  or  950°C.  and 
weigh.  The  amount  of  sulphur  in  BaSC>4  is  13.734  per  cent. 

Attention  should  be  called  to  the  following  notation  made  in 
the  preliminary  report  of  the  committee  on  Methods  of  Sampling 
and  Analysis  of  Coal.1 

(6)  The  Eschka  method  has 
been  long  in  use  and  is  frequently 
the  standard  of  reference.  It 
has  the  disadvantage  of  being 
long  and  requiring  careful  re- 
gard to  sulphur  in  the  reagents 
and  the  gas  used  for  heating. 
,.  The  Eschka  mixture  is  prepared 
by  incorporating  2  parts  of 
magnesium  oxide  with  1  part 
of  sodium  carbonate  and  passing 
through  a  40-mesh  screen. 

FIG.  39.— Cross  section  of  electric  ignition      Weigh  Out  1  gram  of  COal  and 

sulphur  bomb  and  water  jacket.  thoroughly  mix  with  3  grams  of 
the  Eschka  mixture.  This  is  best  carried  out  on  a  sheet  of  glazed 
paper  from  which  it  is  transferred  to  a  No.  0  porcelain  or  other 
suitable  crucible  and  covered  with  about  1  gram  additional  of 
Eschka  mixture.  Heat  gradually  in  a  muffle  till  a  final  tem- 
perature of  approximately  900°C.  or  a  cherry-red  is  attained. 
Continue  the  heating  with  occasional  stirring  for  about  an  hour, 
or  until  all  particles  of  carbon  have  been  burned.  Cool  and 
digest  with  about  100  cc.  of  hot  water  for  J  to  f  hr.  Filter  by 
decantation  and  wash  the  residue  a  number  of,  times  with  hot 
water.  Finally  transfer  to  the  filter  and  wash  four  or  five  times. 
The'filtrate  should  not  exceed  250  cc.  Add  10  to  20  cc.  of  satu- 
rated bromine  water.  Acidify  and  boil  to  expel  the  bromine. 
1  Proc.  Am.  Soc.  for  Testing  Meat,,  vol.  14,  432,  1914. 


SULPHUR  DETERMINATIONS  173 

Make  neutral  to  methyl  orange  by  means  of  NaOH  or  Na2CO 
and  add  1  cc.  excess  of  normal  HC1.  Precipitate  as  under  (a) 
and  complete  the  gravimetric  determination  in  the  usual  manner 
as  there  indicated.  Blank  determinations  should  be  made  on 
the  reagents  employed  and  corrections  applied  to  correspond, 
(c)  The  method  by  fusion  with  sodium  peroxide  is  in  all 
respects  the  most  convenient  to  use.  The  residue  from  a  calori- 
metric  determination  may  be  utilized  or  a  special  bomb  for 
sulphur  determinations  may  be  used.  The  fusion  cup  method  of 
ignition  and  making  up  the  charge  are  the  same  in  either  case. 
Figure  39  shows  the  apparatus  as  assembled  for  firing  by  means 
of  an  electric  current.  The  bomb  cup  alone  with  temporary 
cover  is  shown  in  Fig.  33.  In  this  form  it  is  well  adapted  to 
that  part  of  the  procedure 
which  consists  of  combining  and 
mixing  the  ingredients  of  the 
charge.  One  gram  of  accel- 
erator is  placed  in  the  bottom  of 
the  fusion  cup  and  freed  from 
lumps.  One  measure  of  Na2O2 
is  added  and  thoroughly  mixed 
with  the  accelerator  by  shaking. 
The  \  gram  of  coal  is  then 
added  and  shaken.  Some  opera- 
tors prefer  to  add  the  coal  to 
the  accelerator  and  mix  the  two 
with  a  glass  rod  and  then  add 
the  peroxide  with  subsequent 
thorough  mixing  by  shaking.  If 
the  peroxide  is  not  forgotten  or 
if  the  mixing  by  shaking  is  not 
disregarded  that  procedure  is  a 
good  one.  It  is  sometimes  the 
practice  to  ignite  the  charge  in  FlG'  40--Sulphur  bomb,  common  type, 

!V         .        ,  .  f or  heat  ignition  (actual  size) . 

the  simple  container,  shown  in 

Fig.  40,  by  causing  a  pointed  flame  from  a  blast  lamp  to  impinge 
upon  the  bottom  or  side  of  the  fusion  cup  for  a'brief  period,  suf- 
ficient to  start  the  reaction.  In  such  a  case  it  is  vitally  important 
that  the  mixture  of  coal  and  accelerator  (KC1O3) 'should  be  mixed 
throughout  the  peroxide  which  then  serves  as  a  diluent  and 


174  FUEL,  GAS,  WATER  AND  LUBRICATION 

slows  down  the  reaction  to  a  moderate  speed,  thus  avoiding  the 
explosive  character  of  the  chlorate  and  coal  alone.  If  therefore 
the  Na202  is  forgotten  or  the  mixture  of  coal  and  chlorate  are 
left  undisturbed  at  the  bottom  of  the  fusion  cup,  a  serious 
explosion  may  result. 

A  pointed  flame  from  a  blast  lamp  is  preferred  instead  of  the 
full  flame  of  a  Bunsen  burner.  By  such  means  a  localized  portion 
of  the  fusion  cup  becomes  red  hot  and  ignites  the  charge  at  one 
spot  from  which  the  reaction  proceeds  moderately  throughout 
the  mixture  thus  avoiding  the  violent  reaction  which  may 
accompany  the  use  of  a  full  flame  of  large  volume.  After  igni- 
tion has  started  the  reaction  will  be  complete  in  a  very  short 
time  so  that  after  the  lapse  of  10  or  15  sec.  the  apparatus  may  be 
brought  under  the  tap  for  cooling. 

After  the  reaction  is  complete  and  the  bomb  is  sufficiently  cool 
to  handle,  remove  the  fusion  cup  and  place  in  a  small  beaker  of 
250-cc.  capacity.  Add  water  and  cover  the  beaker  with  a  watch 
glass.  After  solution  is  complete  rinse  and  remove  the  fusion 
cup  and  add  concentrated  HC1  to  the  neutral  point.  This  will 
require  25  to  30  cc.  of  acid.  Add  about  1  cc.  of  normal  acid  in 
excess,  filter  if  necessary,  wash  and  make  up  the  solution  to  about 
225  cc.  Precipitate  the  sulphates  by  means  of  barium  chloride 
exactly  as  indicated  under  (a).  Particular  attention  should  be 
observed  in  washing  the  precipitate  obtained  by  this  method  in 
order  to  remove  all  of  the  soluble  salts  which  are  formed  in  the 
fusion  process. 

(d)  The  photometric  method  for  arriving  at  the  factor  for 
sulphur  is  extensively  used  and  has  many  features  of  advantage 
especially  in  technical  work.  It  is  applicable  to  any  of  the  solu- 
tions obtained  under  (a),  (6),  or  (c)  above,  at  that  point  where 
the  solution  is  ready  for  precipitation  by  means  of  barium 
chloride.  It  is  especially  advantageous  in  method  (c)  where  the 
peroxide  fusion  has  been  employed  for  the  reason  that  separation 
from  the  heavy  alkaline  salts  is  not  involved.  The  details  of 
the  process  are  as  follows:  After  dissolving  out  the  material 
from  the  fusion  cup,  acidify  and  filter  as  directed  under  (c). 
The  precipitation  with  barium  chloride  is  made  in  a  different 
manner  however.  Instead  of  a  coarse  granular  precipitate 
which  will  settle  readily,  a  fine  non-settling  precipitate  is  sought 


SULPHUR  DETERMINATIONS 


175 


which  will  more  nearly  approach  the  colloidal  form.  This  is 
obtained  by  using  crystals  of  BaCl2  and  having  present  also  a 
small  amount  of  oxalic  acid. 

Make  up  the  slightly  acid  solution  to  250  cc.     Measure  out 
50  cc.  for  the  turbidity  test  and  make  up  to  100  cc.     Transfer 


FIG.  41. — Sulphur  photometer. 

this  solution  to  a  suitable  flask  and  add  0.3  to  0.5  gram  of 
barium  chloride  crystals  which  have  been  specially  prepared  by 
sifting  through  a  20  mesh  sieve  and  selecting  for  use  those  which 
are  retained  on  a  30  mesh  sieve.  Without  delay  close  the  flask 
with  the  cork  and  shake  vigorously  for  1  or  2  min.,  then  allow 


176 


FUEL,  GAS,  WATER  AND  LUBRICATION 


to  stand  at  room  temperature,  with  occasional  shaking,  for  5 
to  20  min. 

In  reading  the  turbidity,  the  solution  is  shaken  and  a  portion 
poured  from  the  flask  into  the  wide-mouthed  dropping  funnel, 
a,  Fig.  41.  The  graduated  tube,  d,  is  adjusted  in  the  dark  tube 


zuu 
/90 

/do 

/70 
J6O 

*x 

h/^<? 

«//* 

%  100 
^ 

^    90 

80 
7O 
60 

xa 

\ 

\ 

V 

\ 

\ 

\ 

' 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

* 

\ 

ss 

s 

s 

v^ 

^ 

x 

X 

^ 

X 

.^ 

^ 

^^ 

^> 

^ 

"^ 

^ 

'/.O    /.2     /.4    /.e    /.8    2.O   2.2    2.4    2.6   ^8    3.O  3J2  3.4 

f1/7//ffra/7?s  of  Su/fvr 

FIG.  42. — Typical  curve  for  use  with  sulphur  photometer. 

so  that  the  rounded  lower  end  dips  well  into  the  water,  which 
should  be  about  1  cm.  in  depth  in  the  capsule,  e. 

By  means  of  the  pinch  cock  admit  the  turbid  solution  until 
the  point  of  light  from  the  lamp,  /,  just  disappears,  the  last  point 


SULPHUR  DETERMINATIONS  177 

of  light  being  no  longer  visible.  Do  not  take  account  of  the 
slightly  luminous  center  that  appears  when  the  amount  of  sulphur 
is  high  and  the  readings  are  on  the  lower  portion  of  the  scale,  say 
from  50  to  60  mm.  Take  as  the  end  point  the  complete  disap- 
pearance of  the  light.  Remove  the  tube  and  read  in  milligrams 
the  depth  of  the  liquid.  By  means  of  the  table  or  curve,  Fig. 
42,  is  shown  the  weight  in  milligrams  of  the  sulphur  present  in  the 
100  cc.  of  solution.  If  50  cc.  were  taken  from  the  250-cc.  flask, 
and  this  latter  contained  the  fusion  from  a  J-gram  sample  of 
coal,  then  .the  sulphur  reading  would  be  the  weight  present  in  TV 
gram  of  coal.  By  removal  of  the  decimal  point,  therefore,  one 
place  to  the  right,  there  would  be  shown  the  weight  of  sulphur  in 
1  gram  of  coal  which  can  then  be  read  in  parts  per  100,  or  per 
cent,  by  placing  the  decimal  two  more  places  to  the  right.  If 
read  in  milligrams  each  unit  is  then  1  per  cent.  - 

For  example,  if  the  results  show  a  depth  of  105  mm.,  there 
would  be  indicated  1.78  mg.  of  sulphur  present  in  the  quantity 
taken,  that  is  0.00178  grams.  Now,  if  i  of  the  J  gram  of  coal  is 
represented  in  this  amount,  the  reading  is  for  TV  gram  of  coal. 
For  1  gram  of  coal  there  would  then  be  0.0178  gram  of  sulphur,  or 
1.78  per  cent. 

If  the  sulphur  is  so  great  in  amount  as  to  afford  too  great  turbid- 
ity for  satisfactory  reading,  repeat  the  process,  measuring  out 
25  cc.  of  the  solution  and  diluting  with  water  sufficient  to  make  a 
total  of  100  cc.  in  volume,  and  proceed  as  above  outlined.  After 
multiplying  the  weight  of  the  sulphur  thus  indicated  by  2,  the 
conditions  will  be  the  same  as  indicated  above. 

In  cases  where  the  content  of  sulphur  in  the  coal  is  so  low  that 
the  reading  on  the  tube  comes  above  the  limit  of  graduation,  a 
larger  quantity  of  the  solution  representing  a  greater  amount  of 
coal  should  be  taken.  Thus,  if  we  take  100  cc.  of  the  solution, 
we  will  be  taking  f  of  J  gram  of  the  original  coal  or  J  (0.2)  gram 
of  coal.  Now,  the  sulphur  indicated  on  the  curve  will  be  the 
weight  in  milligrams  which  accompanies  0.20  gram  of  coal.  If, 
therefore,  we  read  the  percentage  as  normally  indicated  and 
divide  by  2,  we  will  have  the  correct  indication  for  the  content  of 
sulphur.  For  example,  if  the  reading  under  these  conditions 
shows  a  depth  of  105  mm.  there  would  be  indicated  1.78  mg.  of 
sulphur^for  the  amount  of  coal  taken,  0.2  gram.  This  would  be 
0.89  mg.  for  0.20  gram  of  coal,  or  0.89  per  cent.1 
12 


178  FUEL,  GAS,  WATER  AND  LUBRICATION 

Special  care  must  be  taken  to  prevent  the  settling  out  of  the 
precipitate.  A  reading  can  be  quickly  made  and  the  contents 
of  the  tube  poured  back  into  the  funnel.  Readings  should  be 
repeated  several  times,  thus  keeping  the  mixture  stirred  and 
affording  greater  accuracy  as  to  the  final  average  taken.  Before 
beginning,  the  bottom  of  the  tube  inside  should  be  cleansed  by 
means  of  a  swab  to  insure  that  no  film  of  precipitate  from  the 
previous  test  has  settled  out. 

For  the  same  reason  be  sure  that  no  sediment  has  settled  out 
on  the  bottom  of  the  cup,  e.  Perfect  alignment  of  the  light 
through  the  diaphragm  and  tube  should  be  secured.  The 
conditions  as  to  strength  of  light,2  methods  of  reading,  the  end 
point,  etc.,  may  vary  from  the  standards  adopted  in  the  table. 
Each  individual  should  check  his  own  method  and  modify  the 
curve  to  correspond  by  making  up  a  solution  of  chemically  pure 
potassium  sulphate,  having  0.5444  gram  per  liter,  which  is  equiva- 
lent to  0.0001  gram  of  sulphur  per  cubic  centimeter.  Use  15  or 
20  cc.  in  making  the  test  and  precipitate  as  in  the  regular  de- 
termination. The  photometer  curve,  Fig.  42,  has  been  developed 
under  the  same  solution  conditions  as  those  accompanying  the 
precipitation  of  the  sulphate  from  the  sodium  peroxide  fusion  in 
which  there  has  been  formed  about  15  grams  of  Nad.  Since 
the  character  of  the  turbidity  precipitate  is  modified  somewhat 
by  the  presence  of  sodium  chloride,  it  is  advisable  that  this 
feature  be  reproduced  in  all  standardization  tests.  The  effect 
of  the  presence  of  sodium  chloride  is  substantially  the  same  for 
any  amount  from  1  to  6  grams  in  each  100  cc.  as  made  ready 
for  the  photometer,  hence  the  most  convenient  procedure  will 
be  to  prepare  a  solution  of  30  grams  of  Nad  in  250  cc.  of 
water  and  use  25  cc.  of  it  in  making  up  the  measured  amount 
of  standard  sulphate  to  100.  Similarly,  the  amount  of  free  HC1 
in  the  100  cc.  volume  should  be  duplicated  by  adding  _2  cc.  of 
cone.  HC1  to  the  250  cc.  solution  of  Nad. 

1  Some  coals,  especially  of  the  semi-bituminous  or  Pocahontas  type,  have 
a  content  of  sulphur  so  low  as  to  make  it  advisable  in  such  cases  to  dissolve 
the  fusion  in  a  smaller  quantity  of  water,  so  that  the  volume  when  made  up 
shall  be  100  cc.     With  sulphur  so  low  as  0.5  per  cent  the  entire  solution  would 
be  required  for  use  with  the  photometer. 

2  A  small  3-volt  tungsten  bulb  with  current  from  two  dry  cells  is  used  as 
a  standard  light. 


CHAPTER  XXIII 

ULTIMATE  ANALYSIS  OF  COAL 

Total  Carbon  Determination. — The  percentage  of  total  carbon 
in  the  coal  used  is  a  necessary  factor  in  determining  the  heat 


/ 


FIG.  43. — Total  carbon  apparatus. 

losses  in  the  flue  gases  as  already  indicated  in  the  discussion  on 
pages  107-110  inclusive.     This  value  may  be  obtained  by  utiliza- 

179 


180  FUEL,  GAS,  WATER  AND  LUBRICATION 

tion  of  the  sodium  peroxide  fusion  in  which  the  total  carbon  of 
the  coal  has  been  oxidized  and  combined  with  chemical  to  form 
Na2CO3.  By  liberating  the  CC>2  under  accurately  determined 
conditions  as  to  temperature  and  pressure  by  means  of  the 
apparatus  shown  in  Fig.  43,  the  amount  of  carbon  present  may 
be  derived  from  the  volume  of  C02  discharged. 

The  apparatus  should  be  located  on  a  laboratory  desk  or  table 
where  an  even  temperature  can  be  maintained. 

Fill  the  jacketing  tube  J  with  water  slightly  acidulated  to  keep 
it  clear.  Fill  the  leveling  tube  L  with  water  that  has  had  2  or 
3  cc.  of  sulphuric  acid  added.  A  few  drops  of  methyl  orange  in 
the  leveling  tube  will  impart  a  color  to  the  water,  greatly  facili- 
tating the  readings. 

Connect  the  inlet  D  with  air  pressure  and  adjust  so  that  two  or 
three  bubbles  of  air  per  second  will  enter  the  jacketing  Vater. 
This  is  for  the  purpose  of  keeping  the  temperature  of  the  water 
equalized  throughout  a  determination .  By  reading  the  thermom- 
eter hung  in  the  water  the  temperature  of  the  gas  under 
observation  is  obtained. 

The  operation  is  as  follows :  The  large  double  pipette  P  is  half 
filled  with  40  per  cent  solution  of  caustic  potash,  or  such  as  is 
ordinarily  used  for  the  absorption  of  C02  gas.  By  turning  the 
three-way  cock  T  to  connect  with  the  pipette  P  and  lowering 
the  leveling  tube  L  the  liquid  in  P  is  brought  into  the  right-hand 
bulb  and  made  to  rise  in  the  capillary  tube  to  the  mark  on  the 
right  limb  of  the  capillary.  The  three-way  cock  is  now  closed 
to  the  pipette  bulb  and  opened  to  the  tube  running  to  the  flask 
B.  By  raising  the  leveling  tube  L  the  liquid  in  the  burette  G  is 
made  to  rise  to  the  three-way  cock  T,  thus  completely  filling  the 
burette.  The  three-way  cock  is  now  closed  to  retain  the  liquid 
in  the  burette  at  the  zero  point,  till  evolution  of  the  gas  is  begun. 

The  cup  containing  the  fused  material  from  a  calorimetric 
determination  is  placed  on  its  side  in  the  bottom  of  a  small 
beaker  and  covered  with  hot  water  that  has  been  boiling  for  5  or 
10  min.  Contamination  with  CO2  from  the  water  used  or  from 
contact  with  the  air  must  be  avoided  as  much  as  possible.  When 
the  fusion  is  dissolved  remove  the  cup,  rinsing  it  well,  and  pour 
the  solution  directly  into  the  flask  B.  Wash  out  the  beaker 
thoroughly  with  hot  water  and  pour  the  washings  in  with  the 


ULTIMATE  ANALYSIS  OF  COAL  181 

main  portion.  Connect  the  flask  with  the  funnel  tube  A  and 
bring  the  ring  support  with  wire  gauze  in  place  under  the  flask. 
Open  the  stop  cock  at  the  lower  end  of  the  funnel  and  boil  the 
contents  of  the  flask  for  3  or  4  min.  Remove  the  flame  and  at 
once  close  the  funnel  cock.  In  this  way  the  oxygen  from  the 
sodium  peroxide  will  be  driven  off  together  with  the  air  in  the 
flask.  Also,  when  the  three-way  cock  T  is  closed  there  will  be  a 
partial  vacuum  in  the  flask. 

With  the  cock  to  the  funnel  tube  A  closed,  enough  acid  is 
added  to  A  to  completely  neutralize  the  alkaline  solution  in  B 
and  leave  a  distinct  excess  of  acid.  Hydrochloric  acid  is  pre- 
ferred. Thirty  cubic  centimeters  of  concentrated  hydrochloric 
acid  will  be  found  sufficient. 

To  operate,  lower  the  leveling  tube  L,  open  the  three-way 
cock  T  to  the  tube  connecting  with  the  flask  B.  and  admit  acid 
drop  by  drop  from  the  funnel  A.  Meantime  the  circulating 
water  for  the  condenser  C  should  be  turned  on. 

When  the  evolution  of  gas  has  about  reached  the  capacity  of 
the  graduated  burette  G,  the  acid  is  shut  off,  the  three-way  cock 
T  closed  and  a  reading  of  the  volume  of  the  gas  carefully  taken 
by  bringing  the  two  surfaces  of  liquid  in  the  leveling  tube  and 
burette  exactly  on  a  level.  Read  also  the  temperature  of  the 
jacketing  water  and  note  the  barometric  pressure.  The  cock  T 
is  now  opened  to  the  capillary  and  the  gas  volume  forced  com- 
pletely over  into  the  bulb  P  where  it  is  held  by  closing  the  cock 
T.  Here  it  is  left  for  complete  absorption  of  the  C02.  The  cock 
T  may  be  again  opened  to  connect  with  the  flask  B,  the  liquid  in 
the  burette  G  being  at  the  zero  point  as  before.  The  apparatus 
is  now  ready  for  a  second  evolution  and  measurement  of  a  gas 
volume. 

A  second  reading  is  similarly  taken  and  the  volume  driven 
over  into  P  as  before,  along  with  the  former  volume.  Repeat 
the  process  until  no  more  C02  is  evolved. 

Finally  heat  is  added  to  the  flask  B  and  after  a  few  minutes 
boiling,  hot  water  is  added  through  the  funnel  A,  until  the  solu- 
tion is  nearly  up  to  the  stopper,  the  flame  of  course  being  re- 
moved. At  this  point  there  should  be  no  water  remaining  in 
the  funnel  A.  Lower  the  leveling  tube  L  to  form  a  partial 
vacuum  and  allow  air  to  be  drawn  through  A  into  B  and  thus 


182 


FUEL,  GAS,  WATER  AND  LUBRICATION 


TABLE  XXI. — WEIGHT  OF  CARBON  IN  MILLIGRAMS 
Calculated  from  1.976  =  weight  of  1  liter  of  CO2  at  41°  latitude 


t/p 

720 

722 

724 

726 

728 

730 

732 

734 

736 

738 

740 

742 

744 

10 

.4851 

.4864 

.4878 

.4891 

.4905 

.4919 

.4933 

.4947 

.4960 

.4974 

.4987 

.5001 

.5014 

11 

.4829 

.4842 

.4856 

.4869 

.4883 

.4896 

.4910 

.4924 

.4937 

.4951 

.4964 

.4978 

.4991 

12 

.4806 

.4819 

.4833 

.4846 

.4860 

.4873 

.4887 

.4901 

.4914 

.4928 

.4941 

.4955 

.4968 

13 

.4783 

.4796 

.4810 

.4823 

.4837 

.4850 

.4864 

.4878 

.4891 

.4905 

.4918 

.4932 

.4945 

14 

.4760 

.4773 

.4787 

.4800 

.4814 

.4827 

.4841 

.4855 

.4868 

.4882 

.4895 

.4908 

.4921 

15 

.4737 

.4750 

.4764 

.4777 

.4791 

.4804 

.4818 

.4832 

.4845 

.4858 

.4871 

.4884 

.4897 

16 

.4714 

.4727 

.4741 

.4754 

.4768 

.4781 

.4795 

.4808 

.4821 

.4834 

.4847 

.4860 

.4873 

17 

.4691 

.4704 

.4718 

.4731 

.4745 

.4758 

.4771 

.4784 

.4797 

.4810 

.4823 

.4836 

.4849 

18 

.4668 

.4681 

.4694 

.4707 

.4721 

.4734 

.4747 

.4760 

.4773 

.4786 

.4799 

.4812 

.4825 

19 

.4644 

.4657 

.4670 

.4683 

.4697 

.4710 

.4723 

.4736 

.4749 

.4762 

.4775 

.4788 

.4801 

20 

.4620 

.4633 

.4646 

.4660 

.4673 

.4686 

.4699 

.4712 

.4725 

.4738 

.4751 

.4764 

.4777 

21 

.4596 

.4609 

.4622 

.4636 

.4649 

.4662 

.4675 

.4688 

.4701 

.4714 

.4727 

.4740 

.4753 

22 

.4572 

.4585 

.4598 

.4612 

.4625 

.4638 

.4651 

.4664 

.4677 

.4690 

.4703 

.4716 

.4729 

23 

.4548 

.4561 

.4574 

.4587 

.4600 

.4613 

.4626 

.4639 

.4652 

.4665 

.4678 

.4691 

.4704 

24 

.4523 

.4536 

.4549 

.4562 

.4575 

.4588 

.4601 

.4614 

.4627 

.4640 

.4653 

.4666 

.4679 

25 

.4498 

.4511 

.4524 

.4537 

.4550 

.4563 

.4576 

.4589 

.4602 

.4614 

.4627 

.4640 

.4653 

26 

.4473 

.4486 

.4499 

.4512 

.4524 

.4537 

.4550 

.4563 

.4576 

.4588 

.4601 

.4614 

.4627 

27 

.4447 

.4460 

.4473 

.4486 

.4498 

.4511 

.4524 

.4537 

.4550 

.4562 

.4575 

.4588 

.4601 

28 

.4421 

.4434 

.4447 

.4460 

.4472 

.4485 

.4498 

.4511 

.4524 

.4536 

.4549 

.4562 

.4575 

29 

.4395 

.4408 

.4420 

.4433 

.4445 

.4458 

.4471 

.4484 

.4497 

.4509 

.4522 

.4535 

.4548 

30 

.4368 

.4381 

.4393 

.4406 

.4418 

.4431 

.4444 

.4457 

.4470 

.4482 

.4495 

.4508 

.4521 

31 

.4341 

.4354 

.4366 

.4379 

.4391 

.4404 

.4417 

.4430 

.4443 

.4455 

.4468 

.4481 

.4494 

32 

.4314 

.4327 

.4339 

.4352 

.4364 

.4377 

.4390 

.4402 

.4415 

.4427 

.4440 

.4453 

.4466 

33 

.4286 

.4299 

.4311 

.4324 

.4336 

.4349 

.4362 

.4374 

.4387 

.4399 

.4412 

.4425 

.4438 

34 

.4258 

.4271 

.4283 

.4296 

.4308 

.4321 

.4334 

.4346 

.4359 

.4371 

.4384 

.4396 

.4409 

35 

.4230 

.4242 

.4255 

.4267 

.4280 

.4292 

.4305 

.4317 

.4330 

.4342 

.4355 

.4367 

.4380 

sweep  out  the  residual  gas  in  the  connecting  tubes  into  the 
burette  C.  The  amount  of  air  thus  drawn  in  should  be  slightly 
more  than  100  cc.  so  that  after  transferring  to  the  bulb  P  for 
final  absorption  of  the  remaining  C02,  the  air  returned  to  the 
graduated  burette  will  be  sufficient  in  amount  to  bring  the  level 
down  upon  the  graduated  portion  of  the  burette  for  reading. 
The  difference  between  this  volume  and  the  total  of  the  several 
volumes  is  the  total  carbon  dioxide  present  in  the  fusion. 

By  referring  to  Table  XXI,  there  is  found  at  the  observed 
temperature  and  pressure  the  weight  in  milligrams  of  carbon  in 
1  cc.  of  C02  gas.1  Multiply  this  weight  by  the  number  of  cubic 
centimeters  obtained  in  the  above  operation  and  the  product 
equals  the  weight  in  milligrams  of  pure  carbon.  From  this 

1  See  also  PARR,  S.  W.,  The  weight  of  carbon  dioxide  with  a  table  of  calcu- 
lated values,  Jour.  Am.  Chem.  Soc.,  vol.  21,  p.  237,  1909. 


ULTIMATE  ANALYSIS  OF  COAL 


183 


PER  CUBIC  CENTIMETER  OF  COa 

Corrected  for  water  vapor  and  barometer-glass  scale 


t/p 

746 

748 

750 

752 

754 

756 

758 

760 

762 

764 

766 

768 

770 

10 

.5028 

.5041 

.5055 

.5069 

.5083 

.5096 

.5110 

.5124 

.5137 

.5151 

.5165 

.5178 

.5192 

11 

.5005 

.5018 

.5032 

.5046 

.5060 

.5073 

.5087 

.5101 

.5114 

.5127 

.5141 

.5154 

.5168 

12 

.4982 

.4995 

.5009 

.5023 

.5036 

.5049 

.  5063 

.5077 

.  5090 

.5103 

.5117 

.5130 

.5144 

13 

.4959 

.4972 

.4986 

.4999 

.5012 

.5025 

.5039 

.5053 

.5066 

.5079 

.5093 

.5106 

.5120 

14 

.4935 

.4948 

.4962 

.4975 

.4988 

.5001 

.5015 

.5029 

.5042 

.5055 

.5069 

.5082 

.5096 

15 

.4911 

.4924 

.4938 

.4951 

.4964 

.4977 

.4991 

.5005 

.5018 

.5031 

.5045 

.5058 

.5072 

16 

.4887 

.4900 

.4914 

.4927 

.4940 

.4953 

.4967 

.4981 

.4994 

.5007 

.5021 

.5034 

.5048 

17 

.4863 

.4876 

.4890 

.4903 

.4916 

.4929 

.4943 

.4957 

.4970 

.4983 

.4997 

.5010 

.5024 

18 

.4849 

.4852 

.4866 

.4879 

.4892 

.4905 

.4919 

.4933 

.4946 

.4959 

.4973 

.4986 

.4999 

19 

.4815 

.4828 

.4842 

.4855 

.4868 

.4881 

.4895 

.4908 

.4921 

.4934 

.4948 

.4961 

.4974 

20 

.4791 

.4804 

.4818 

.4831 

.4844 

.4857 

.4870 

.4883 

.4896 

.4909 

.4923 

.4936 

.4949 

21 

.4767 

.4780 

.4793 

.4806 

.4819 

.4832 

.4845 

.4858 

.4871 

.4884 

.4898 

.4911 

.4924 

22 

.4742 

.4755 

.4768 

.4781 

.4794 

.4807 

.4820 

.4833 

.4846 

.4859 

.4873 

.4886 

.4899 

23 

.4717 

.4730 

.4743 

.4756 

.4769 

.4782 

.4795 

.4808 

.4821 

.4834 

.4847 

.4860 

.4873 

24 

.4692 

.4705 

.4718 

.4731 

.4744 

.4757 

.4770 

.4783 

.4795 

.4808 

.4821 

.4834 

.4847 

25 

.4666 

.4679 

.4692 

.4705 

.4718 

.4731 

.4744 

.4757 

.4769 

.4782 

.4795 

.4808 

.4821 

26 

.4640 

.4653 

.4666 

.4679 

.4692 

.4705 

.4718 

.4731 

.4743 

.4756 

.4769 

.4782 

.4795 

27 

.4614 

.4627 

.4639 

.4652 

.4665 

.4678 

.4691 

.4704 

.4716 

.4729 

.4742 

.4755 

.4768 

28 

.4587 

.4600 

.4612 

.4625 

.4638 

.4651 

.4664 

.4677 

.4689 

.4702 

.4715 

.4728 

.4741 

29 

.4560 

.4573 

.4585 

.4598 

.4611 

.4624 

.4637 

.4650 

.4662 

.4675 

.4688 

.4701 

.4714 

30 

.4533 

.4546 

.4558 

.4571 

.4584 

.4597 

.4610 

.4623 

.4635 

.4647 

.4660 

.4673 

.4686 

31 

.4506 

.4519 

.4531 

.4544 

.4556 

.4569 

.4582 

.4595 

.4607 

.4619 

.4632 

.4645 

.4658 

32 

.4478 

.4491 

.4503 

.4516 

.4528 

.4541 

.4554 

.4567 

.4579 

.4591 

.4604 

.4617 

.4603 

33 

.4450 

.4463 

.4475 

.4488 

.4500 

.4512 

.4525 

.4538 

.4550 

.4562 

.4575 

.4588 

.4601 

34 

.4421 

.4434 

.4446 

.4459 

.4471 

.4483 

.4496 

.4509 

.4521 

.4533 

.4546 

.4559 

.4572 

35 

.4392 

.4405 

.4417 

.4430 

.4442 

.4454 

.4467 

.4479 

.4492 

.4504 

.4517 

.4529 

.4542 

should  be  subtracted  the  weight  of  carbon  found  by  running  a 
blank  in  exactly  the  same  manner,  using  one  measure  of  the 
sodium  peroxide  instead  of  the  fusion. 

After  subtracting  the  blank,  the  carbon  remaining  represents 
the  total  carbon  present  in  the  fuel.  Divide  this  number  by  the 
weight  of  fuel  taken  and  multiply  by  100.  The  product  is  the 
per  cent  of  carbon  present  in  the  sample  taken. 

Coals  with  calcium  carbonate  present  should  have  the  C02 
in  that  combination  determined  and  the  total  carbon  factor 
corrected  accordingly.  Five  grams  of  coal  should  be  put  into 
the  flask  and  treated  precisely  as  for  a  fusion.  The  amount  of 
carbon  found  from  the  volume  of  CO2  liberated  is  subtracted 
from  the  total  carbon  as  obtained  from  the  fusion.  This  of 
course  is  in  addition  to  the  CO2  found  in  the  blank  determination 
in  the  Na2O2. 


184  FUEL,  GAS,  WATER  AND  LUBRICATION 

Hydrogen. — The  hydrogen  is  determined  by  calculation  as 
already  discussed  in  Part  I,  page  49.  At  this  stage  in  the  de- 
velopment of  the  work  it  is  well  to  transfer  the  factors  involved 
to  the  unit  coal  basis.  Calculate  the  B.t.u.  for  unit  coal.  Calcu- 
late also  the  percentage  of  total  carbon  present  in  the  unit  coal, 
exclusive  of  course  of  any  carbon  present  as  calcite.  From  the 
total  carbon  (C  X  14,545)  in  which  C  is  the  percentage  of  carbon 
in  the  unit  coal.  The  remaining  heat  is  due  to  the  combustion 
of  the  available  hydrogen.  Divide  this  remainder  by  the  ac- 

/     ff    \ 
cepted  value  for  hydrogen  (62  QOQ)  m  wmcn  H  is  the  residual 

heat  after  subtracting  the  heat  due  to  the  combustion  of  the 
carbon. 

Oxygen. — Assuming  a  value  in  the  unit  coal  for  nitrogen  of  1.75 
per  cent.,  we  would  have  the  residual  constituents,  R  consisting 
of  oxygen  and  the  hydrogen  combined  as  H20  represented  by  the 
expression  R  =  100  -  (C  +  H  +  N). 

In  the  value  thus  found  for  R,  the  combined  hydrogen  would 
be  one-ninth  and  the  oxygen  eight-ninths  of  that  value. 

The  values  thus  obtained  on  unit  coal  are  to  be  calculated 
back  to  the  "dry"  by  multiplying  each  value  by  1  minus  the  ash 
corrected  for  hydration  and  sulphur. 


CHAPTER  XXIV 

FUEL  GAS  ANALYSIS 

Introduction. — The  types  of  fuel  gases  have  already  been 
discussed  in  Part  I,  pages  89  and  90.  An  examination  of  the  con- 
stituents present  in  these  various  gases  shows  that  while  there  are 
large  variations  in  the  percentage  composition,  the  constituents 
themselves  are  quite  uniform  as  to  kind.  For  this  reason  it  is 
possible  and  exceedingly  convenient  to  assemble  in  one  apparatus 
the  individual  units  for  making  the  several  determinations. 
Moreover,  portability  is  not  an  essential  feature  for  such  work, 
hence  the  development  of  what  may  be  properly  referred  to  as  an 
enlarged  Orsat  for  making  a  complete  analysis  of  any  of  the 
various  types  of  fuel  gases. 

Description  of  Apparatus. — The  apparatus,  Fig.  44,  consists  of 
two  parts,  the  first  being  a  graduated  and  a  blank  companion 
burette,  which  assures  measurements  at  atmospheric  pressures, 
and  an  attached  leveling  bulb.  By  means  of  these  the  sample  is 
measured  before  the  analysis  is  begun  and  also  after  the  removal 
of  each  constituent.  The  burettes  and  leveling  bulb  are  filled 
with  a  saturated  salt  solution  which  may  be  slightly  colored,  if 
desired,  with  some  inorganic  salt  as  NiN03,  to  aid  in  reading  the 
graduations  on  the  burette,  a.  The  jacket  surrounding  these 
two  burettes  is  filled  with  water  slightly  acidulated  to  keep  it- 
clear.  The  second  part  is  a  stand  supporting  seven  absorption 
pipettes,  one  copper  oxide  furnace  and  one  slow  combustion 
pipette.  These  are  connected  to  the  measuring  burette  by 
means  of  a  manifold  of  capillary  glass  tubing  and  stop  cocks,  this 
being  divided  into  three  parts,  as  is  shown  by  the  figure,  to 
facilitate  manufacture,  assembling  and,  when  necessity  demands, 
repairing.  All  stop  cocks  through  which  gas  is  passed  should 
have  the  plug  or  core  bored  at  an  angle,  as  they  are  then  less 
apt  to  leak.  All  of  the  stop  cocks  in  the  apparatus  should  be 
kept  well  lubricated  with  a  special  stop-cock  grease.1  Care  must 

1  WHITE,  ALFRED  H.,  ''Technical  Gas  and  Fuel  Analysis,"  p.  17. 

185 


186 


FUEL,  GAS,  WATER  AND  LUBRICATION 


also  be  taken  not  to  pull  the  reagents  in  the  pipettes  up  into  the 
stop  cocks  as  this  will  cause  them  to  stick;  this  is  especially  true 
of  KOH  and  Pyrogallol,  and  if  such  a  mistake  is  made  the  stop 
cocks  must  at  once  be  carefully  cleaned  and  greased.  The 
absorption  pipettes  are  the  same  as  those  used  in  the  ordinary 
Orsat  flue  gas  analysis  outfits  and  have  the  chamber  into  which 


FIG.  44. — Modified  Orsat  apparatus. 

the  gas  is  drawn  filled  with  glass  tubes  to  increase  the  surface 
and  obviate  the  necessity  of  shaking. 

The  so-called  copper  oxide  furnace  is  an  ordinary  chromel  wire 
resistance  furnace,  wound  on  an  alundum  core,  insulated  with 
sil-o-cel  and  contained  in  a  metal  jacket.  It  has  been  found  that 
40  ft.  of  No.  24  chromel  wire  makes  a  satisfactory  heating  ele- 


FUEL  GAS  ANALYSIS  187 

ment.  The  current  for  such  an  element  is  taken  from  the  110- 
volt  alternating-current  lighting  circuit  which  may  be  connected 
directly  without  danger  of  burning  out  the  element.  This, 
however,  will  heat  the  furnace  higher  than  is  desired  and  it  is 
necessary  to  connect  a  lamp-bank  resistance  in  series  with  the 
heating  element  in  order  to  maintain  the  desired  temperature. 
The  lamp  bank  is  not  shown  in  the  figure,  but  may  be  seen  in  the 
photograph,  Fig.  22,  page  96.  The  furnace  is  placed  over  the 
pyrex  U-tube,  j.  The  U-tube  is  filled  completely  with  copper 
oxide  that  has  been  ground  to  pass  through  a  20-mesh  sieve  and 
has  been  caught  on  a  40-mesh  sieve.  The  oxide  is  revived  from 
time  to  time  by  passing  oxygen  through  it  while  it  is  at  the 
reactive  temperature  of  300°C. 

The  slow  combustion  pipette,  i,  is  made  from  a  300  cc.  pyrex 
Kjeldahl  digesting  flask.  It  is  connected  to  the  manifold  with 
a  small  capillary  tube  which  must  be  carefully  sealed  on  so  that 
the  orifice  is  no  larger  than  the  bore  of  the  tubing.  This  will 
cause  the  gas  to  enter  the  pipette  in  a  small  jet  and  eliminate  the 
liability  of  explosive  mixtures  during  the  manipulation  of  the 
pipette.  The  bottom  of  the  pipette  is  closed  with  a  three-hole 
rubber  stopper  which  accommodates,  besides  the  outlet  of  the 
pipette,  two  glass  tubes  at  the  inner  ends  of  which  is  sealed  a 
platinum  coil.  This  coil  is  placed  about  J  in.  below  and  slightly 
to  one  side  of  the  opening  of  the  capillary  tube.  It  is  connected 
in  series  with  a  chromel  sliding  contact  resistance  (not  shown  in 
the  figure).  The  outlet  from  the  pipette  connects,  by  means  of 
rubber  tubing  and  the  stop  cock,  w,  with  the  small  aspirator 
bottle,  q.  Mercury  is  used  in  this  part  of  the  apparatus  instead 
of  salt  water. 

Oxygen  and  nitrogen  are  used  during  the  procedure  of  the 
analysis.  These  are  kept  at  hand  in  large  aspirator  bottles 
over  water,  and  are  connected  permanently  with  the  apparatus 
by  means  of  rubber  tubing.  The  stop  cock,  s,  connects  with 
the  nitrogen  bottle  and  ra,  with  the  oxygen  bottle.  The  sample 
of  gas  is  usually  collected  and  stored  over  saturated  salt  water  in 
a  small  aspirator  bottle  and  is  drawn  from  this  into  the  burette,  a, 
through  a  rubber  tube  connected  to  the  stop  cock,  x,  which  has  a 
key  extension  for  the  rubber  tubing  and  is  similar  to  the  stop 
cock,  m. 


188  FUEL,  GAS,  WATER  AND  LUBRICATION 

Manipulation  and  Description  of  Reagents. — Before  beginning 
an  analysis,  make  sure  that  none  of  the  stop  cocks  leak  or  other- 
wise need  attention,  and  that  trie  level  of  the  solutions  in  all  of  the 
pipettes  is  up  to  the  mark.  Next  sweep  the  manifold  and  copper 
oxide  tube  thoroughly  with  nitrogen  drawing  it  in  through  the 
stop  cock,  s,  and  expelling  it  through  the  stop  cock,  x.  It  is  also 
well  to  have  brought  the  copper  oxide  furnace  up  to  the  required 
temperature  of  300°  before  the  analysis  is  begun  and  to  have  made 
sure  that  the  nitrogen  enclosed  in  it  is  at  atmospheric  pressure. 
Otherwise  due  to  expansion  there  will  be  a  slight  change  in  the 
reading  on  the  burette,  when  the  stop  cocks,  I  and  r,  are  opened 
during  the  analysis,  which  will  probably  be  overlooked  and  which 
will  make  an  error  in  the  hydrogen  determination.  Having 
observed  the  above  precautions  and  having  the  burette,  a,  filled 
with  salt  solution  completely  up  to  the  stop  cock,  x,  the  sample 
bottle  is  connected  with  the  stop  cock,  x,  by  means  of  a  rubber 
tube  that  has  been  thoroughly  flushed  with  the  gas  to  be 
analyzed.  A  sample  of  slightly  over  100  cc.  is  drawn  into  the 
burette.  The  companion  tube,  n,  has  been  opened  to  the  atmos- 
phere and  the  solution  in  it  is  at  the  same  level  as  in  the  bulb,  t, 
which  should  be  slightly  below  the  level  of  the  100  cc.  graduation 
on  the  burette,  a.  Without  closing  the  stop  cock,  x,  the  rubber 
tube  is  disengaged  from  the  sample  bottle,  but  not  from  the  stop 
cock,  and  the  bulb,  t,  is  raised  until  the  solution  in  it  and  the  two 
burettes  are  at  the  same  level  and  at  the  100-cc.  mark  in  the 
burette,  a.  The  stop  cocks,  x  and  u,  are  now  closed  and  the 
burette,  a,  contains  exactly  100  cc.  of  the  gas  at  atmospheric 
pressure.  Since  all  other  parts  of  the  apparatus  are  filled  with 
the  inert  gas,  nitrogen,  and  since  all  future  volume  readings 
during  this  analysis  will  be  made  at  the  same  pressure,  the  con- 
tractions will  all  be  on  the  basis  of  the  100-cc.  sample  at  atmos- 
pheric pressure  and  will  be  in  per  cent  by  volume  directly.  It  is 
assumed  that  the  atmospheric  pressure  will  not  change  during  the 
analysis.  No  corrections  need  to  be  made  on  account  of  the  gas 
being  saturated  with  water  vapor.  During  the  analysis  the 
leveling  bulb,  t,  is  held  in  the  left  hand  and  by  being  raised  or 
lowered,  the  gas  is  forced  into  the  various  pipettes  or  drawn  back 
into  the  burette,  a.  In  measuring  the  sample  during  the  analysis, 
the  stop  cock,  u,  is  opened  and  with  the  aid  of  the  leveling  bulb, 


FUEL  GAS  ANALYSIS  189 

the  solutions  in  burettes,  a  and  n,  are  brought  to  the  same  level. 
The  stop  cock,  v,  is  now  closed  and  the  volume  read  on  the  burette, 
a.  This  volume  is  written  down  at  once  and  the  analysis  con- 
tinued by  closing  the  stop  cock,  u,  opening  v,  and  with  the  aid  of 
the  bulb,  t,  forcing  the  sample  into  the  next  desired  portion  of 
the  apparatus. 

Now  that  the  apparatus  contains  a  sample  of  exactly  100  cc.  of 
gas,  the  next  step  is  the  removal  of  the  constituent  carbon  dioxide. 
The  first  pipette,  b,  contains  about  150  cc.  of  40  per  cent  KOH.1 
White  specifies  25  per  cent  NaOH  for  the  absorption  of  carbon 
dioxide,  but  in  the  author's  laboratory  it  has  been  found  that 
KOH  is  a  faster  reagent  and  also  has  a  greater  capacity  for 
carbon  dioxide.  It  may  be  used  until  it  shows  considerable 
carbonate  precipitate  and  still  seems  to  be  as  active  as  when 
freshly  made.  The  stop  cocks,  x,  m,  I,  and  the  one  at  the  top  of 
the  pipette,  6,  are  opened  so  that  by  raising  the  leveling  bulb,  t, 
the  gas  in  burette,  a,  will  be  driven  into  the  pipette.  The  gas 
is  forced  from  a  to  b  and  back  several  times,  usually  five  will  be 
sufficient,  until  it  shows  no  further  reduction  in  volume.  The 
difference  between  this  final  constant  volume  and  the  original 
100  cc.  will  be  the  per  cent  of  carbon  dioxide  in  the  sample.  It 
might  be  well  to  note  that  if  the  gas  contains  hydrogen  sulphide,  it 
will  also  be  removed  by  the  KOH  and  thus  give  a  slight  error  in 
the  carbon  dioxide  value.  Hydrogen  sulphide  may  be  determined, 
when  in  sufficient  quantity,  by  passing  the  gas  first  into  a  pipette 
filled  with  a  solution  of  arsenious  acid.2  In  this  case  the  removal 
of  carbon  dioxide  would  come  second  in  the  procedure. 

Oxygen  is  next  removed  by  passing  the  sample  several  times 
into  the  pipette,  c,  which  contains  an  alkaline  solution  of  pyro- 
gallol,  made  by  mixing  equal  volumes  of  33  per  cent  KOH  and 
25  per  cent  pyrogallic  acid.3  One  volume  of  this  reagent  is  able 
to  absorb  about  eight  volumes  of  oxygen.  The  reagent  will 
deteriorate  quite  rapidly  if  exposed  to  the  air  and  it  is  well  to 
connect  the  secondary  pipette  with  a  small  rubber  balloon  to 
eliminate  deterioration  in  this  manner.  After  removal  of  all  the 
oxygen,  the  volume  of  the  gas  is  taken.  The  difference  between 

1  WHITE,  ALFRED  H.,  "Technical  Gas  and  Fuel  Analysis,"  p.  72,  1920. 

2  Loc.  tit. 

3  WHITE,  ALFRED  H.,  "Technical  Gas  and  Fuel  Analysis,"  p.  33,  1920. 


190  FUEL,  GAS,  WATER  AND  LUBRICATION 

this  volume  and  the  volume  after  removing  the  carbon  dioxide 
is  the  per  cent  of  oxygen  in  the  sample  of  gas. 

Oxygen  may  be  removed  from  the  gas  with  yellow  phosphor- 
us.1 This  is  sometimes  desirable  especially  when  the  percentage 
of  oxygen  is  rather  high,  on  account  of  the  relatively  small 
capacity  of  the  pyrogallol.  The  phosphorus  in  the  form  of  small 
sticks  is  placed  in  the  pipette,  instead  of  the  glass  rods,  and  is 
covered  with  water.  On  passing  the  gas  to  be  analyzed  into 
the  phosphorus  pipette,  the  oxygen  unites  with  the  phosphorus 
forming  solid  oxides  of  phosphorus.  However,  when  phosphorus 
is  used  to  remove  oxygen,  the  gas  must  have  been  previously 
freed  from  ethylene  and  benzene,  as  these  will  poison  the  phos- 
phorus and  make  it  inactive.  Phosphorus  is  considered  a  very 
good  reagent  for  oxygen  but  its  use  in  the  apparatus  in  the 
author's  laboratory  has  been  rather  unsatisfactory  on  account 
of  its  being  affected  by  light,  its  ease  of  being  poisoned  and  its 
slowness  of  reaction. 

The  sample  of  gas  after  removal  of  oxygen  by  means  of  the 
pyrogallol  is  passed  into  the  pipette,  d,  which  is  filled  with 
bromine  water.  This  removes  ethylene  and  any  other  unsatu- 
rated  hydrocarbons  that  may  be  present.  Before  reading  the 
new  volume  to  determine  the  per  cent  of  ethylene  removed,  it  is 
necessary  to  pass  the  sample  a  few  times  into  the  KOH  pipette  to 
remove  the  bromine  fumes  and  thus  give  the  correct  volume. 
The  bromine  solution  is  saturated  with  bromine  and  is  main- 
tained saturated  by  keeping  a  few  drops  of  bromine  in  the  bottom 
of  the  pipette  at  all  times.  As  long  as  the  solution  is  maintained 
in  a  saturated  condition,  it  will  never  cease  to  function. 

Benzene2  is  removed  by  passing  the  sample  into  the  pipette,  e, 
which  contains  fuming  sulphuric  acid.  This  reagent  will  also 
remove  any  ethylene  that  is  in  the  gas  at  this  time  and  in  some 
procedures  is  used  for  both  ethylene  and  benzene,  the  two 
being,  when  determined  together,  considered  as  illuminants.  The 
reagent  used  in  this  apparatus  is  the  ordinary  20  per  cent  fuming 
sulphuric  acid  and  it  is  considered  active  as  long  as  it  shows  S03 
fumes  when  the  sample  is  forced  into  the  pipette.  These  fumes 
must  be  removed  from  the  sample  of  gas  by  means  of  the  KOH 

1  WHITE,  "  Technical  Gas  and  Fuel  Analysis,"  p.  30,  1920. 

2  WHITE,  ALFRED  H.,  "Technical  Gas  and  Fuel  Analysis,"  p.  85,  1920. 


FUEL  GAS  ANALYSIS  191 

pipette  before  the  resultant  volume  is  read  for  the  same  reasons 
that  the  bromine  fumes  were  removed. 

This  concludes  the  absorption  methods  in  the  ordinary  analysis 
and  the  next  step  is  the  determination  of  hydrogen  and  carbon 
monoxide  by  use  of  the  copper  oxide  furnace,  already  described. 
It  is  assumed  that  this  furnace  is  at  a  temperature  of  300°C. 
and  that  the  enclosed  nitrogen  is  at  atmospheric  pressure  this 
having  been  attended  to  at  a  previous  time.  The  stop  cocks,  I 
and  r,  are  turned  to  bring  the  U-tube,  j,  in  series  with  the  rest  of 
the  manifold  and  the  gas  sample  is  forced  through  the  U-tube 
and  into  the  pipette,  h.  This  pipette  is  filled  with  saturated 
salt  solution  and  does  not  necessarily  need  to  be  filled  with 
glass  rods  as  it  merely  acts  as  a  reservoir  for  the  gas  sample. 
On  passing  the  gas  through  the  hot  copper  oxide,  combustion 
of  the  hydrogen  and  carbon  monoxide  takes  place,  the  former 
burning  to  water  and  condensing  out,  while  the  latter  burns  to 
carbon  dioxide  and  remains  in  the  sample  but  occupies  the  same 
space  as  did  the  carbon  monoxide.  Thus  the  contraction  in 
volume  is  due  entirely  to  the  removal  of  the  hydrogen  from  the 
sample  of  gas,  and  if  the  sample  is  passed  back  and  forth  through 
the  copper  oxide  until  its  volume  becomes  constant,  the  con- 
traction will  give  directly  the  per  cent  of  hydrogen  that  was 
originally  in  the  sample.  As  the  reactive  temperature  of  carbon 
monoxide  with  copper  oxide  is  lower  than  that  of  hydrogen,  it 
may  be  assumed  that  when  all  of  the  hydrogen  has  been  removed, 
all  of  the  carbon  monoxide  will  be  burned  to  carbon  dioxide. 
After  reading  the  volume  and  determining  the  percentage  of 
hydrogen  in  the  gas,  sufficient  nitrogen  is  drawn  in  through  the 
stop  cock,  s,  to  completely  sweep  the  tube,  j,  of  any  of  the  sample. 
The  gas  in  the  burette  is  placed  at  atmospheric  pressure  and  the 
stop  cocks,  I  and  r,  are  returned  to  their  original  position.  The 
volume  of  the  sample  which  is  now  increased  due  to  the  added 
nitrogen  is  read  and  noted  as  "new  volume."  The  sample  is  now 
forced  into  the  pipette,  b,  several  times  to  remove  the  carbon 
dioxide  resulting  from  the  burning  of  the  carbon  monoxide. 
The  resultant  volume  is  read  and  the  difference  between  this 
volume  and  the  last  read  or  "new  volume"  gives  directly  the 
per  cent  of  carbon  monoxide  that  was  present  in  the  gas. 

The  sample   of  gas  now  contains  presumably   nothing  but 


192  FUEL,  GAS,  WATER  AND  LUBRICATION 

methane,  ethane  and  nitrogen,  although  there  probably  are 
instances  where  some  of  the  higher  paraffin  homologues  are 
present.  The  amounts  of  paraffins  are  determined  by  burning 
in  an  atmosphere  of  oxygen  in  the  slow  combustion  pipette,  i, 
the  ignition  being  due  to  the  electrically  heated  platinum  coil, 
o.  The  mechanics  of  the  determination  are  as  follows:  Store 
the  sample  temporarily  in  the  pipette,  h.  Draw  oxygen  into  the 
burette,  a,  through  the  stop  cock,  m,  measure  the  volume  at 
atmospheric  pressure  and  then  force  it  into  the  pipette,  i.  From 
150  to  200  cc.  of  oxygen  is  usually  necessary,  which  means  that 
a  second  burette  full  must  be  forced  into  the  pipette  i.  The 
approximate  volume  of  oxygen  needed  can  be  estimated  by 
knowing  previously  something  concerning  the  amounts  of 
methane  and  ethane  present  in  the  sample.  The  sample  is  next 
drawn  back  into  the  burette,  a,  and  placed  under  slight  pressure 
by  putting  the  bulb,  t,  in  the  upper  holder  as  shown  in  the 
figure.  The  level  of  the  mercury  in  the  pipette,  i,  will  be  below 
the  tips  of  the  glass  rods,  as  shown  in  the  figure.  The  stop 
cock,  w,  is  open  and  the  mercury  level  in  the  bottle,  q,  is  slightly 
lower  than  in  the  pipette,  z,  thus  giving  a  slight  vacuum  in  the 
pipette.  The  stop  cock,  y,  in  the  manifold,  leading  to  the 
pipette,  i,  is  closed.  The  electric  current  is  next  passed  through 
the  platinum  coil  heating  it  to  a  bright-red  or  almost  white 
heat.  It  is  now  time  to  admit  the  sample  from  the  burette. 
Carefully  open  the  stop  cock,  y,  slightly,  and  do  not  let  go  of  it, 
thus  controlling  the  flow  of  gas  into  the  pipette.  It  should  burn 
at  once  with  a  small  luminous  jet  from  J  to  f  in.  in  length  and 
not  directed  upon  the  platinum  coil.  Watch  carefully  the  flow 
of  the  gas  from  the  burette,  a,  and  when  the  burette  is  full  of  water, 
close  the  stop  cock,  y,  from  which  the  hand  has  not  been  removed. 
Immediately  turn  off  the  electric  current.  If  the  above  direc- 
tions are  not  carefully  followed  a  dangerous  explosion  may  occur 
when  the  attempt  is  made  to  burn  the  paraffins.  The  hydro- 
carbon gas,  CnH2n  +  2,  in  the  sample  has  burned  to  water  and 
carbon  dioxide.  The  water  has  condensed  out  and  may  be  seen 
on  the  surface  of  the  mercury.  It  is  forced  up  the  capillary 
tube  when  the  resultant  gas  is  withdrawn  from  the  pipette,  i,  and 
finds  its  way,  usually,  into  the  pipette,  h,  by  settling  into  the 
vertical  tubing  above  the  stop  cock  until  that  stop  cock  is  turned 


FUEL  GAS  ANALYSIS  193 

during  the  next  analysis.  No  special  attention  is  given  to  the 
elimination  of  the  water  from  the  pipette,  i,  but  it  is  the  usual 
practice  to  bring  the  level  of  the  mercury  up  to  the  stop  cock, 
y,  after  each  determination,  and  thus  the  water  in  the  pipette,  i, 
is  maintained  at  a  minimum. 

It  is  now  necessary  to  measure  back  the  volume  of  gas  in  the 
combustion  pipette  and  determine  the  carbon  dioxide  that  it 
contains.  First,  place  the  level  of  the  mercury  in  the  bottle,  q, 
above  that  in  the  pipette,  i,  thus  preventing  the  salt  solution  in 
the  burette,  a,  being  pulled  over  into  the  pipette,  i,  when  the 
stop  cock,  y,  is  opened.  Measure  the  resultant  gas,  pass  it  into 
the  pipette,  b,  to  remove  the  carbon  dioxide  and  measure  the 
volume  a  second  time.  From  the  readings  taken  during  the 
procedure,  as  just  described,  four  values  are  available.  These 
are:  (1)  The  volume  of  the  gas  sample  burned.  '(2)  The  volume 
of  oxygen  taken.  (3)  The  volume  of  the  resultant  gas  after 
combustion.  (4)  The  volume  of  carbon  dioxide  in  the  resultant 
gas.  The  contraction,  due  to  the  condensation  of  water,  is 
obtained  by  subtracting  (3)  from  the  sum  of  (1)  and  (2).  By 


substituting  these  values  in  the  formula  V  =  -      0  it  is 

o 

possible  to  calculate  the  volume  of  the  paraffins  present  in  the 

f-*O 

sample.     And  by  substituting  in  n  =  ~^-9  the  index  of  average 

composition  of  the  paraffins  is  obtained.  The  derivation  and 
application  of  these  formulas  is  more  fully  discussed  in  Part  I, 
page  99. 

The  sum  of  the  percentages  of  the  constituents  so  far  deter- 
mined should  not  be  100.  The  difference  between  their  sum 
and  100  therefore  is  taken  as  the  percentage  of  nitrogen  in  the 
original  sample.  This  nitrogen  value  since  it  is  obtained  by 
difference,  must  of  course  carry  all  of  the  errors  of  the  several 
determinations.  Experience  would  seem  to  indicate,  however, 
that  these  are  small  in  amount. 

Of  the  seven  absorption  pipettes  only  five  are  used  in  the 
ordinary  analysis.  The  two  extra  pipettes  are  included  in  the 
apparatus  for  additional  reagents  that  may  be  needed  in  case 
of  analyzing  special  gases,  as  for  example,  it  may  be  desired  to 
fill  a  pipette  with  arsenious  acid  for  the  removal  of  hydrogen 

13 


194 


FUEL,  GAS,  WATER  AND  LUBRICATION 


1 


sulphide,  or  the  gas  may  contain  acetylene  which  can  be  removed 
directly  after  oxygen  by  passing  into  a  pipette  filled  with  ammoni- 
acal  silver  chloride.1  The  ammonia  fumes  must  be  removed  by 
passing  the  gas  into  a  pipette  of  weak  sulfuric  acid 
before  the  reading  is  taken.  The  desirability  of  a 
phosphorus  pipette  has  previously  been  discussed.  In 
case  the  two  extra  pipettes  are  not  filled  with  special 
reagents,  it  is  well  to  fill  them  with  saturated  salt 
solutions  as  they  may  often  be  used  as  storage  reser- 
voirs for  samples  of  gas  to  be  analyzed. 
/^The  Determination  of  Sulphur  in  Gas. — Gas  regula- 
tions usually  prescribe  the  limit  for  hydrogen  sulphide 
as  well  as  for  total  sulphur. 

In  gas  works  practice,  a  ready  test  for  hydrogen  sul- 
phide is  used  in  the  shape  of  filter  paper  moistened 
with  lead  acetate.  The  method  has  quantitative  pos- 
sibilities of  sufficient  accuracy  for  indicating  the  com- 
pleteness of  purification  in  the  manufacturing  process. 
The  Bureau  of  Standards,  in  Circular  32,  recommends 
the  following  as  a  standard  form  of  specification:  "The 
gas  shall  be  considered  to  contain  not  more  than  a 
trace  of  hydrogen  sulphide  if  a  strip  of  white  filter  paper 
FIG.  45.—  moistened  with  a  solution  containing  5  per  cent  by 
sulphide  weight  of  lead  acetate  is  not  distinctly  darker  than  a 
indicator.  secon(j  paper  freshly  moistened  with  the  same  solu- 
tion after  the  first  paper  has  been  exposed  to  the  gas  for  one 
minute  in  an  apparatus  of  approved  form  through  which  the  gas 
is  flowing  at  the  rate  of  approximately  5  cu.  ft.  per  hour,  the  gas 
not  impinging  from  a  jet  upon  the  test  paper."  An  apparatus 
for  this  test  is  shown  in  U.  S.  Bureau  of  Standards  Circular 
48,  p.  118,  and  may  easily  be  made  with  an  ordinary  8  in.  cylin- 
drical gas  chimney  of  about  \%  in.  in  diameter  with  stoppers  at 
each  end.  A  5-ft.  burner  jet  is  installed  above,  and  the  pillar 
of  an  ordinary  gas  burner  below.  Arrangements  for  spreading 
the  gas  at  the  intake  and  a  support  for  the  test  paper  are  shown 
in  Fig.  45.  A  hardened  filter  paper  with  smooth  surface  is 
preferred.  It  should  be  moist  and  suspended  vertically  midway 
between  the  watchglass  below  and  the  cork  above. 

1  WHITE,  ALFRED  H.,  "Technical  Gas  and  Fuel  Analysis,"  p.  85,  1920. 


D 


FUEL  GAS  ANALYSIS 


195 


Gas  Inlet 
FIG.  46. — Junker  calorimeter  showing  details  of  construction. 


196  FUEL,  GAS,  WATER  AND  LUBRICATION 

The  total  sulphur  in  gas  is  determined  either  by  the  Referee's 
apparatus  or  by  the  Drehschmidt  method.  The  former  is 
described  in  the  Bureau  of  Standards  Circular  48  and  is 
probably  more  frequently  employed  in  gas  works  practice.  The 
two  methods  are  similar,  differing  chiefly  in  the  mechanism 
employed.  The  Drehschmidt  method  is  made  use  of  in  the 
author's  laboratory  and  consists  of  3  wash  bottles  connected  to 
the  vacuum  system  or  a  water  jet  pump.  The  gas  is  burned 
under  a  trumpet  tube  which  is  connected  to  the  washing  train 
for  delivering  the  products  of  combustion  to  the  alkaline  wash 
bottles  which  have  a  5  per  cent  solution  of  Na2C03  with  a  few 
drops  of  bromine  water  or  a  small  amount  of  Na2C>2  added  to  each 
bottle.  The  burning  of  2J  feet  of  gas  is  sufficient  for  a  test  and 
the  burner  should  consume  about  1  cu.  ft.  per  hour.  The  meter, 
barometer,  and  thermometer  readings  are  taken  at  the  beginning 
and  ending  of  a  test.  The  solutions  are  transferred  to  a  beaker, 
made  slightly  acid  with  HC1  and  reduced  in  bulk  by  evaporation 
if  necessary.  Add  about  1  cc.  excess  of  normal  acid  and  deter- 
mine the  sulphur  by  means  of  the  photometer  or  gravimetrically 
in  the  usual  manner. 

Direct  Determination  of  Heating  Value. — The  calorimeters 
most  frequently  used  in  determining  the  heating  value  of  fuel 
gas  are  of  the  continuous  flow  type.  The  first  instrument 
designed  in  1893  by  Hugo  Junkers1  with  minor  changes  is  the 
standard  instrument  at  the  present  time.  The  general  installa- 
tion has  already  been  shown  in  Fig.  21.  A  cross  section  here 
given  in  Fig.  46  will  be  of  assistance  in  following  the  operation 
of  the  instrument. 

A  Bunsen  burner  delivers  the  heat  from  the  gas  into  the  com- 
bustion chamber.  Since  it  is  essential  that  all  of  the  heat  be 
extracted  from  the  spent  gases,  their  discharge  must  be  at  the 
bottom  of  the  apparatus  instead  of  at  the  top,  the  gases  in  the 
downtake  being  heavier  than  those  in  the  combustion  chamber. 
The  principle  involved  is  therefore  similar  to  that  of  a  siphon 
for  liquids.  In  order  to  secure  an  even  flow  of  water  through 
the  instrument,  a  constant  head  is  maintained  by  means  of  an 
overflow  cup.  On  the  way  down,  the  water  passes  the  inlet 
thermometer  and  is  admitted  near  the  bottom  of  the  instrument 

lJournafur  Gasbel,  Vol.  36,  p.  81  (1898), 


FUEL  GAS  ANALYSIS  197 

through  a  regulating  valve.  The  water  flowing  upward  collects 
in  the  neck  of  the  heater  and  passes  the  outlet  thermometer  into 
a  second  constant  overflow  cup  from  which  it  may  be  directed 
either  to  the  weighing  bucket  or  to  the  waste.  The  water  of 
condensation  forms  only  in  the  down-take  passageways  and 
collects  at  the  bottom  where  an  outlet  is  provided. 

Operation  of  the  Junker  Calorimeter. — The  directions  for 
operating  the  calorimeter  as  prescribed  by  the  technical  com- 
mittee of  the  American  Gas  Institute  are  essentially  as  follows : 

Connect  the  meter  to  the  governor  and  the  governor  to  the 
burner  with  short  pieces  of  rubber  tubing,  or  with  flexible  metal 
tubing  having  coupled  ends. 

The  calorimeter  should  be  set  up  in  a  quiet,  light  and  well 
ventilated  room  or  cabinet,  which  is  free  from  draughts  and  in 
which  the  temperature  can  be  maintained  constantly  at  not 
less  than  60°F.  The  room  should  be  provided  with  a  sink  and 
large  shallow  overhead  covered  tank,  from  which  the  water 
supply  can  be  taken.  Should  the  tank  capacity  be  small  and 
not  hold  enough  water  for  a  prolonged  series  of  readings,  a  small 
gas  water  heater  may  be  employed  to  bring  the  water  to  approxi- 
mately the  room  temperature.  It  is  desirable  to  use  water  that 
is  clear  and  free  from  suspended  matter  in  the  calorimeter, 
therefore,  a  filter  should  be  installed  in  the  water  supply  line 
before  it  enters  the  overhead  tank. 

If  only  a  single  test  is  desired,  gas  may  be  taken  from  the  house 
piping,  but  if  an  average  value  is  required,  a  small  gas  holder,  or 
averaging  tank,  should  be  used,  and  the  gas  flowing  into  the 
holder  adjusted  to  a  rate  of  flow  to  just  fill  it  in  the  time  during 
which  the  sample  is  to  be  taken.  Care  should  be  taken  to  have 
a  short  service  to  this  holder  in  order  that  an  average  sample  of 
gas  may  be  obtained,  and  if  the  sample  be  taken  from  a  line  on 
which  there  is  no  considerable  consumption,  see  that  this  line  is 
thoroughly  purged  before  sampling.  It  is  recommended  that 
the  gas  be  metered  at  a  pressure  not  to  exceed  two  inches  of 
water ;  if  this  is  not  obtainable,  it  is  advisable  to  insert  a  holder 
or  diaphragm  governor  in  the  supply  line  to  reduce  the  pressure 
to  within  this  limit. 

Make  water  connections  with  rubber  tubing,  being  careful 
not  to  cramp  the  tubing.  To  avoid  air  currents  caused  by  the 


198  FUEL,  GAS,  WATER  AND  LUBRICATION 

movement  of  the  observer's  body,  set  up  the  calorimeter  so  that 
the  water  supply  and  waste  may  be  easily  adjusted  and  that  all 
temperatures  may  be  readily  observed.  Lead  the  outlet  water 
to  a  waste  funnel  supported  a  little  above  the  top  of  the  copper 
or  glass  container  used  in  collecting  the  water,  so  that  the  water 
can  be  shifted  from  the  funnel  to  the  container  and  back  without 
spilling. 

Set  up  the  gas  meter  facing  the  observer  and  level  it  carefully. 
Then  adjust  the  water  level  of  the  meter,  both  inlet  and  outlet 
being  open  to  the  air.  If  the  meter  has  been  filled  with  fresh 
water,  the  gas  must  be  allowed  to  burn  at  least  two  hours  before 
making  a  test.  When  the  water  in  the  meter  is  saturated  with 
gas,  20  minutes  should  be  sufficient. 

Fill  pressure  regulator  with  water,  about  %  full,  then  connect 
it  to  the  calorimeter  burner.  Metallic  tubing  is  preferable,  but 
when  rubber  tubing  is  used  to  connect  meter,  pressure  regulator, 
and  burner,  connections  should  be  as  short  as  possible,  and  should 
be  saturated  with  the  gas. 

Turn  on  the  gas  and  allow  it  to  burn  for  five  to  ten  minutes  with 
the  burner  on  the  table.  Shut  off  the  gas  at  burner  and  watch 
the  hand  on  the  meter  for  leakage.  Be  sure  that  all  leaks  are 
stopped  before  attempting  to  make  a  test.  Start  water  running 
through  the  calorimeter  at  a  rate  of  about  3  pounds  per  minute. 
Then  regulate  the  gas  to  flow  at  the  rate  of  4  to  7  feet  an  hour, 
as  may  be  found  by  experiment  to  give  the  highest  result  with 
the  gas  to  be  tested,  admitting  enough  air  through  the  burner 
so  that  the  flame  shows  a  faint  luminous  tip,  then  insert  the 
burner  as  far  up  into  the  combustion  chamber  as  the  bracket 
permits,  and  observe  again  the  condition  of  the  flame  to  see  that 
it  is  all  right,  using  a  mirror. 

The  excess  of  air  passing  through  the  calorimeter  is  controlled 
somewhat  by  the  position  of  the  damper.  Some  experimentation 
may  be  necessary.  Operate  the  calorimeter  until  a  thermal 
balance  is  established  on  the  inlet  and  outlet  water  thermometers. 
Start  with  the  damper  closed,  then  open  slightly,  observing 
carefully  the  outlet  thermometer.  When  this  thermometer 
reads  at  a  maximum — or  in  other  words,  when  the  greatest  rise 
in  temperature  is  given  to  the  water,  which  is  presumable  passing 
through  the  calorimeter  uniformly — the  damper  is  in  approxi- 


FUEL  GAS  ANALYSIS  199 

mately  the  correct  position  for  the  amount  of  gas  being  burned, 
and  the  excess  air  necessary  for  perfect  combustion  is  at  a  mini- 
mum. 

Water  should  be  regulated  so  that  there  is  a  difference  between 
the  inlet  and  outlet  temperatures  of  about  15°F.  The  tempera- 
ture of  the  inlet  water  should  vary  but  little  when  an  overhead 
tank  is  used  and  the  water  maintained  at  room  temperature. 
Be  sure  that  both  overflows  are  running. 

Before  making  the  test,  the  barometer,  temperature  of  the  gas 
at  the  meter,  temperature  of  room  and  temperature  of  exhaust 
products  should  be  recorded.  It  is  desirable  to  have  the  tem- 
perature of  the  inlet  water  and  temperature  of  exhaust  products 
as  nearly  as  possible  at  room  temperature,  in  order  to  establish 
more  nearly  a  thermal  balance — the  difference  in  these  tempera- 
tures should  never  exceed  5°. 

Next  allow  the  gas  to  burn  in  the  calorimeter  until  a  thermal 
balance  is  established,  or  until  there  is  the  least  change  in  the 
inlet  and  outlet  waters.  The  condensed  water  should  also 
commence  to  drip  showing  an  equilibrium  status  within  the 
calorimeter. 

The  test  may  now  be  started  by  shifting  the  outlet  water 
from  the  funnel  to  the  container  just  as  the  large  hand  on  the 
meter  passes  the  zero  point.  Readings  are  then  made  of  the  inlet 
and  outlet  thermometers,  making  the  readings  as  rapidly  as  the 
observer  is  able  to  record  them  during  the  consumption,  prefer- 
ably of  two-tenths  of  a  cubic  foot  of  gas.  At  least  ten  readings 
should  be  made  of  both  inlet  and  outlet  water  temperatures. 
Water  is  again  shifted  from  the  container  to  the  waste  funnel 
as  the  hand  passes  the  zero  point  the  second  time.  Water  is  then 
weighed  or  measured.  The  uncorrected  heating  value  per  cubic 
foot  is  obtained  by  multiplying  the  difference  of  the  average  of 
inlet  and  outlet  temperatures,  by  the  number  of  pounds  of  water 
and  by  dividing  by  two-tenths.  This  quantity  is  divided  by  the 
correction  factor  for  barometer  and  temperature,  obtainable 
from  the  tables  in  the  Appendix,  to  give  the  heating  value  at  30 
inches  pressure  and  60°F.  The  weight  or  contents  of  the  con- 
tainer should  be  obtained  while  the  inside  is  wet.  This  may  be 
done  by  filling  it  with  water,  emptying  and  shaking  for  about 
five  seconds  in  an  inverted  position.  This  will  do  away  with 


200  FUEL,  GAS,  WATER  AND  LUBRICATION 

any  correction  where  several  consecutive  tests  are  required  with 
the  same  container. 

A  second,  and  perhaps  a  third  test  is  advisable,  and  these 
should  be  made  without  disturbing  the  existing  conditions, 
provided  all  readings  are  within  the  above  prescribed  limits.  In 
practice  the  operator  should  get  consecutive  results  on  the  same 
holder  of  gas  within  ten  (10)  B.t.u. 's.  Under  such  conditions  an 
average  of  the  results  may  safely  be  taken.  The  water  of  con- 
densation should  be  caught  in  a  50  cc.  graduate  so  that  calcula- 
tion can  be  made  for  the  net  heating  value  if  desired.  It  is 
better  to  collect  the  condensate  from  a  total  of  1  cu.  ft.  for 
making  the  estimate.  The  latent  heat  of  vaporization  for  water 
at  the  initial  temperature  of  the  gas  and  air  is  taken  as  0.600 
Calories,  hence  the  number  of  cubic  centimeters  of  condensed 
water  from  1  cu.  ft.  of  gas  multiplied  by  0.600  X  3.968  will  equal 
the  B.t.u.  to  be  subtracted  from  the  total  observed  values  as 
given  by  the  calorimeter  for  the  net  B.t.u. 


CHAPTER  XXV 

THE  ANALYSIS  OF  FLUE  GASES 

Reagents. — The  analyses  to  be  made  in  this  course  will  be 
performed  with  what  is  known  as  the  "Orsat  apparatus,"  Fig.  47. 
This  is  made  of  a  jacketed  100-cc.  gas  burette  and  leveling  bottle 
permanently  connected  by  a  capillary  tube  having  four  side 
arms  to  three  pipettes  and  to  the  open  air.  The  end  of  the 


FIG.  47. — Orsat  apparatus. 

capillary  tube  extends  outside  the  case  for  conveninece  in  taking  a 
sample  of  gas.  The  pipettes  are  provided  with  reagents,  as  follows : 
1.  Potassium  hydroxide,  for  absorption  of  carbon  dioxide, 
CO2.  Strength  of  solution,  40  per  cent.  One  cubic  centimeter 
absorbs  40  cc.  of  carbon  dioxide. 

201 


202  FUEL,  GAS,  WATER  AND  LUBRICATION 

2.  Potassium    pyrogallate    for    absorption    of    oxygen,    62. 
Equal  volumes  of  33  per  cent  KOH  and  25  per  cent  pyrogallic 
acid  solutions  are  mixed  together.     One  cubic  centimeter  will 
absorb  8  cc.  of  oxygen. 

3.  Cuprous  chloride  for  the  absorption  of  carbon  monoxide, 
CO.     A  solution  of  cuprous  chloride  is  prepared  by  dissolving 
Cu2Cl2  in  hydrochloric  acid  sp.  gr.  1.12  in  the  ratio  of  15  grams 
of  the  salt  to  100  cc.  of  acid.     The  activity  of  the  solution  depends 
on  the  presence  of  copper  in  the  cuprous  form.     If  pure,  the 
solution  would  be  colorless.     It  turns  green  upon  oxidation.     It 
should  be  kept  from  the  light  and  occasional  additions  of  copper 
wire  or  turnings  made  to  the  accessory  pipette  or  the  stock  bottle. 

Analysis  of  Atmospheric  Air. — Adjust  the  reagent  in  each 
pipette  by  drawing  the  solution  up  into  the  capillary  tube  to  the 
mark  just  below  the  rubber  connection.  Fill  the  jacketed 
measuring  burette  with  water  out  to  the  end  of  the  capillary 
tube,  then  draw  in  a  little  over  100  cc.  of  air  by  opening  the 
outer  vent  and  lowering  the  leveling  bottle.  Next,  slowly  raise 
the  leveling  bottle  until  the  meniscus  gives  a  reading  of  exactly 
zero,  and  the  level  of  the  water  in  the  burette  is  just  equal  to 
that  in  the  leveling  bottle. 

(a)  Oxygen. — Close  the  pinch  cocks  on  all  vents  and  open  the 
one  on  the  second  pipette,  the  one  containing  potassium  pyrogal- 
late; now  raise  the  leveling  tube  slowly,  thus  forcing  the  air  into 
the  pipette.  When  the  water  has  reached  the  100-cc.  mark  on 
the  burette,  shut  the  pinch  cock  and  allow  to  stand  for  5  min. 
Now  open  the  cock  and  run  the  gas  back  into  the  burette  by 
lowering  the  leveling  bottle.  Watch  the  surface  of  the  pyrogal- 
late solution,  and  as  it  approaches  the  mark  slow  up  the  flow  of 
gas — by  careful  manipulation  of  the  leveling  bottle  the  solution 
can  be  brought  just  to  the  mark  and  then  shut  off,  giving  much 
more  delicate  adjustment  than  can  be  obtained  by  manipulation 
of  the  pinch  cock  alone.  It  is  very  important  that  none  of  these 
solutions  get  above  the  pinch  cock,  as  the  potassium  hydroxide 
in  them  interferes  with  the  carbon  dioxide  determinations  in 
subsequent  samples. 

Repeat  the  absorption  for  3  min.  and  read  again.  The  con- 
traction in  volume  is  due  to  absorption  of  oxygen.  Calculate  the 
percentage  on  the  sample  taken. 


THE  ANALYSIS  OF  FLUE  GASES  203 

The  Analysis  of  Respired  Air. — The  apparatus  should  be  in 
adjustment  after  the  preceding  experiment.  Take  a  long  breath 
and  hold  in  the  lungs  for  some  time,  then  blow  it  into  one  of  the 
rubber  balloons.  Attach  this  to  the  outer  vent  of  the  apparatus 
and  draw  in  a  sample  of  110  cc.  as  before.  Now  close  this  pinch 
cock  and  open  the  one  at  right  angle,  to  the  air;  then,  by  raising 
the  leveling  bottle  slowly,  bring  the  surface  of  the  water  to  the 
zero  mark  and  close  the  cock  opening  to  the  air. 

(a)  Carbon  Dioxide. — Always  absorb  the  carbon  dioxide  first 
bringing  the  gas  into  the  first  or  potassium  hydroxide  pipette. 
Allow  it  to  stand  for  5  min.  and  repeat  for  3  min.  The  contrac- 
tion is  due  to  carbon  dioxide — determine  its  percentage. 

(6)  Oxygen. — Determine  oxygen  as  in  the  case  of  atmospheric 
air.  The  difference  between  the  total  contraction  and  the  first 
one  is  due  to  oxygen.  Compute  the  percentage. 

(c)  Nitrogen. — This  is  determined  by  difference. 

100  -  (C02  +  02)  =  N2 

Flue  Gas. — All  determinations  of  the  constituents  of  flue  gas 
are  carried  out  as  described  above  for  "  Respired  Air." 

Carbon  monoxide  is  determined  after  oxygen  by  means  of  the 
third  pipette,  allowing  the  gas  to  stand  for  8  min.  In  calculating 
nitrogen,  the  amount  of  CO  is  of  course  taken  into  consideration. 


CHAPTER  XXVI 

ANALYSIS  OF  BOILER  WATERS 

Normal  Solutions. — If  the  reaction  between  one  solution  and 
another  can  be  gaged  exactly  as  to  the  "end  point,"  that  is,  if 
that  point  can  be  noted  where  an  exact  balance  exists  between 
the  two  reacting  substances,  we  may  make  use  of  these  solutions 
as  media  for  making  chemical  measurements,  just  as  a  mechanic 
uses  a  foot  rule  for  measuring  lengths.  Given,  therefore,  a 
solution  of  known  value,  that  is,  a  standard  solution,  and  a 
reaction  where  the  end  point  or  chemical  equilibrium  can  be 
made  visible  to  the  eye  by  any  means,  we  have  a  method  which 
can  be  used  to  measure  other  solutions  of  unknown  value.  When 
a  standard  solution  has  its  chemical  value  made  up  in  terms  of  the 
molecular  weight  of  the  substance  in  grams  per  liter,  it  is  called  a 
molal  solution.  It  is  more  convenient,  however,  to  make  up 
such  solutions  on  the  basis  of  the  hydrogen  equivalent  of  the 
part  of  the  molecule  concerned,  in  order  to  avoid  the  necessity 
of  multiplying  or  dividing  by  two  where  ions  of  different  valencies 
interact.  Thus, 

2HC1  +  Na2CO3  =  2NaCl  +  H2CO3  would  call  for  two 
molecular  quantities  of  HC1  and  one  of  Na2C03  or  one  of  HC1 
and  \  of  Na2CO3.  Again, 

HC1  +  Na2CO3  =  NaCl  +  NaHCO3  would  call  for  one  full 
molecular  quantity  of  HC1  and  one-half  of  the  molecular  value 
for  the  Na2CO3.  By  common  agreement  the  single  hydrogen 
equivalent  has  been  adopted  as  the  basis,  and  solutions  of  this 
kind  are  called  normal  solutions.  Hence,  a  normal  solution  of 
the  first  substance,  HC1,  has  exactly  36.46  grams  per  liter.  A 
normal  solution  of  the  second  has  exactly  53.00  grams  or  one-half 
of  the  molecular  weight,  106.0,  of  sodium  carbonate  per  liter. 
Where  solutions  of  less  strength  are  needed,  tenth  or  hun- 

N         N 
dredth  normal   solutions  are  used,   expressed  thus:  7^  or  ^-^ 

1U  1UU 

204 


ANALYSIS  OF  BOILER  WATERS  205 

N 
Thus,  JQ  sodium  carbonate  has  5.300  grams  of  the  pure  substance 

per  liter  and  each  cubic  centimeter  contains  0.0053  gram  of  the 
alkali. 

It  is  important  that  the  full  significance  and  value  of  the  proc- 
esses involving  normal  solutions  be  well  understood  at  the  outset 
of  the  work.  The  preliminary  experiments  following  will  help 
to  this  end. 

EXERCISE  I 

N 
Standard  Sodium  Carbonate. — The  preparation  of  y~  sodium 

carbonate  solution  is  carried  out  as  follows : 

Clean  and  dry  a  porcelain  crucible  or  small  porcelain  dish,  then 
ignite  it  lightly  and  cool  down  to  room  temperature,  putting  into 
the  desiccator  at  about  150°.  Weigh  accurately  and  add  about 
6  grams,  more  or  less,  of  pure,  dry  sodium  carbonate.  Raise  to 
a  red  heat,  short  of  melting,  and  cool  in  a  desiccator.  Counter- 
poise upon  the  balance  in  such  a  manner  that  by  removing  with  a 
clean  knife  blade  or  spatula  the  excess  of  material,  there  shall 
remain  in  the  crucible  exactly  5.300  grams  of  the  carbonate. 
Empty  the  carbonate  into  a  No.  3  beaker  and  add  50  or  100  cc. 
of  distilled  water.  Rinse  out  the  crucible  also  a  number  of  times, 
adding  the  washings  to  the  beaker.  After  solution  of  the  car- 
bonate is  complete,  pour  the  contents  of  the  beaker  into  a  liter 
measuring  flask.  Rinse  out  the  beaker  thoroughly,  transferring 
the  washings  to  the  flask  and  make  up  finally  to  the  mark.  The 
temperature  of  the  water  employed  for  making  up  to  volume 
should  not  exceed  20°C.  Stopper  and  mix  by  shaking  until  an 
absolute  certainty  of  uniform  distribution  of  the  solution  is 
attained.  If  the  sodium  carbonate  is  pure  and  the  proper  care 
in  regard  to  transferring,  mixing,  temperature,  etc.,  has  been 

N 
observed,  we  should  now  have  a  strictly  ^Q  solution.     To  test 

its  accuracy,  obtain  from  the  instructor  some  of  the  ready  pre- 

N 
pared  TQ  hydrochloric  acid  solution  and  proceed  as  follows. 

Measure  about  20  cc.  of  the  sodium  carbonate  from  a  burette 
into  a  clean  beaker.  Add  about  20  cc.  of  water  and  2  drops  of 


206  FUEL,  GAS,  WATER  AND  LUBRICATION 

N 

methyl  orange  solution.  Titrate  very  slowly  with  JQ  hydro- 
chloric acid  from  a  burette.  Add  acid  drop  by  drop  until  the 
yellow  turns  to  an  orange  color.  More  acid  will  make  the  solu- 
tion pink,  but  this  is  too  far — the  intermediate  orange  tint 
denotes  neutrality.  More  accurate  results  will  be  obtained 
if  the  solutions  are  titrated  back  and  forth  until  one  drop  of 
either  solution  will  change  the  color  of  the  indicator.  Repeat 
this  titration  three  times  and  average  the  results.  The  quantity 
of  acid  required  should  not  vary  from  the  solution  taken  by 
more  than  0.1  cc.  If  there  is  a  greater  difference  than  this,  the 
strength  of  the  sodium  carbonate  solution  may  be  calculated 
from  the  known  hydrochloric  acid  solution.  This  correction 

N 
is  known  as  the  y^  factor.     The  factor  must  be  taken  into 

consideration  whenever  the  sodium  carbonate  solution  is  used. 

N 
The  exactly  y/y  solutions  are  much  to  be  preferred  where  a  large 

number  of  determinations  are  being  made.  What  applies 
to  the  sodium  carbonate  solution  is  equally  true  with  all  standard 

N 
solutions  that  are  used.     From  the  yg  sodium  carbonate  solution 

N 
make  a  ^  sodium  carbonate  solution. 

EXERCISE  II 

N 
Standard  Sulphuric  Acid. — Prepare  a  y~  solution  of  sulphuric 

N 
acid  by  means  of  the  y~  Na2C03  solution  as  follows: 

Measure  about  3J  cc.  of  pure  concentrated  sulphuric  acid  into  a 
flask  containing  1,050  cc.  of  distilled  water.  Mix  thoroughly  and 
fill  a  50-cc.  burette  with  the  solution.  Measure  20  cc.  from  the 
burette  into  a  clean  beaker,  add  about  20  cc.  of  water  and  2 

N 

drops  of  methyl  orange.  Titrate  slowly  with  y~  sodium  car- 
bonate solution  from  a  burette  until  the  end  reaction  is  shown 
by  the  first  change  of  color  from  pink  to  orange.  Repeat  the 
titration  as  before,  being  careful  to  note  the  correct  color  for  the 


ANALYSIS  OF  BOILER  WATERS  207 

end  point.     The  acid  solution  is  probably  too  strong.     If  the 

N 
titration  with  y^  sodium  carbonate  requires,  say,  21  cc.  instead 

of  20  cc.,  then  in  such  case  20  cc.  of  acid  would  need  to  be  diluted 
to  21  cc.  to  make  an  exact  balance  to  the  alkali  solution.  Simi- 
larly 200  cc.  would  need  to  be  diluted  to  210  cc.  and  the  dilution 
for  any  amount  would  be  indicated  by  the  proportion 

20  :21  ::  1,000  :x 

Hence,  in  the  above  example,  measure  an  exact  1,000  cc.  of  the 
trial  acid  and  add  50  cc.  of  pure  water  to  it.  Test  the  accuracy 

N 
of  the  resulting  solution  with  y^  sodium  carbonate  as  before. 

EXERCISE  III 

Determination  of  Sulphur. — (Consult  also  the  description  for 
the  determination  of  sulphur  under  " Sulphur  Determinations," 
page  174). 

N 
Measure  out  10  cc.  of  the  y~  sulphuric  acid  solution  and  make 

up  to  100  cc.  Measure  carefully  10  cc.  of  this  solution  into  a  100 
cc.  cylinder.  Add  25  cc.  of  the  NaCl  solution  described  on  page 
178  and  make  up  to  the  100  mark,  pour  into  an  Erlenmeyer  flask 
and  add  about  0.2  to  0.4  gram  of  special  barium  chloride  crystals 
(BaCl2)  and  shake  thoroughly.  Let  stand  for  5  to  20  min.  with 
occasional  shaking.  Read  the  depth  of  liquid  in  the  photometer 
tube  at  which  the  light  completely  disappears.  Repeat  the  read- 
ings two  or  three  times.  If  the  column  is  less  than  60  or  more 
than  160  mm.  in  depth,  reject  the  test  and  start  anew  using  double 
or  half  the  quantity  of  solution  under  test,  making  up  to  100  cc. 
in  each  case  as  before. 

In  Chapter  XXII,  page  176,  will  be  found  a  curve  on  which  is 
indicated  the  number  of  grams  of  sulphur  per  100  cc.  of  solution 
corresponding  to  the  various  heights.  Calculate  the  weight  of 
sulphur  indicated  to  sulphuric  acid.  Note  that  the  actual  amount 

N 
of  the  y~  solution  taken  for  the  test  is  1  cc. 

N 
One  cubic  centimeter  of  y~  sulphuric  acid  has  what  weight  of 

acid  present? 


208  FUEL,  GAS,  WATER  AND  LUBRICATION 

How  much  sulphur? 

What  would  be  the  equivalent  amount  of  hydrochloric  acid? 
Sodium  carbonate?     Calcium  carbonate? 


EXERCISE  IV 

Standard  Calcium  Chloride  and  Soap  Solutions. — Measure 

N 
from  a  burette  into  a  clean  No.  2  beaker  40  cc.  of  T~  hydrochloric 

acid.  What  equivalent  does  it  contain  in  terms  of  sodium  car- 
bonate? What  equivalent  in  terms  of  calcium  carbonate? 
Weigh  carefully  0.210  gram  of  pure  calcium  carbonate  powder 

N 
and  add  it  to  the  40  cc.  of  y~  hydrochloric  acid.     Cover  with  a 

watch  glass  and  heat  for  a  few  minutes  till  all  action  has  ceased. 
Transfer  to  a  liter  flask.  Wash  out  the  beaker  thoroughly  with 
distilled  water,  transferring  the  washings  to  the  flask.  Make  up 
to  the  mark  and  mix  thoroughly  by  shaking.  Allow  the  con- 
tents to  stand  quietly  until  all  undissolved  material  has  settled  to 
the  bottom.  Siphon  off  half  or  more  of  the  clear  solution  into 
a  suitable  flask  and  label  "  STANDARD  CALCIUM  CHLORIDE 

N 
SOLUTION."     Since  1  cc.  of  a  y~  solution  is  equivalent  to  1  cc. 

N 
of  any  other  r~  solution,  we  have  in  the  above  solution  40  cc.  of 

N 
a  JQ  CaCl2  solution.     Although  calcium  carbonate  is  not  soluble 

N 
in  water,  the  40  cc.  of  ^  calcium  chloride  is  equivalent  to  the 

N 
amount  of  calcium  carbonate  in  40  cc.  of  a  theoretical  |~  solution 

N 
of  calcium  carbonate.     Since  in  1  cc.  of  a  ^  solution  of  calcium 

carbonate  there  are  0.005  gram  of  calcium  carbonate,  in  the  40 
cc.  of  hydrochloric  acid  solution  or  the  liter  of  solution  there  are 
0.2  gram  of  calcium  carbonate.  The  standard  calcium  chloride 
solution,  therefore,  has  a  value  of  200  parts  per  million  in  terms  of 
calcium  carbonate. 


ANALYSIS  OF  BOILER  WATERS 


209 


The  standard  soap  solution  is  prepared  by  dissolving  10  grams 
of  castile  soap  in  100  cc.  of  80  per  cent  alcohol.  After  standing 
for  several  days  it  is  further  diluted  with  70  per  cent  alcohol  to  a 
point  where  5  or  6  cc.  of  it  as  measured  from  a  burette  will 
produce  a  permanent  lather  when  added  as  directed  below  to  20 


100 


90 


80 


<370 

I 

i 

u,  60 


50 


30 


Cubic  Centimeters  Soap  Solution 

FIG.  48. — Development  of  the  curve  for  a  standard  soap  solution  with  the 
points  located  as  follows: 

Point  No.  1,  using  10  cc.  CaCh  sol. 
Point  No.  2,  using  15  cc.  CaCh  sol. 
Point  No.  3,  using  20  cc.  CaCh  sol. 
Point  No.  4,  using  25  cc.  CaCh  sol. 


cc.  of  the  standard  calcium  chloride  solution.     This  will  require 
usually  a  dilution  up  to  900  or  1,000  cc. 

Standardization  of  the  Soap  Solution. — Measure  20  cc.  of  the 
standard  calcium  chloride  solution  into  a  250  cc.  glass-stoppered 
bottle  and  add  30  cc.  of  distilled  water.  Run  in  from  a  burette 

14 


210  FUEL,  GAS,  WATER  AND  LUBRICATION 

the  standard  soap  solution  0.4  or  0.5  cc.  at  a  time,  shaking  the 
bottle  vigorously  after  each  addition.  Lay  the  bottle  on  its 
side  after  each  shaking  and  note  if  the  lather  remains.  The  end 
point  is  taken  where  the  lather  remains  over  the  entire  surface 
of  the  water  for  5  min.  after  shaking.  Make  three  tests  of  the 
standard  calcium  chloride  solution  as  above  prepared.  Repeat 
the  process,  using  10  cc.  of  the  calcium  chloride  solution  and 
making  up  to  the  same  volume  (addition  of  40  cc.  water)  as 
before.  By  thus  establishing  a  number  of  points  as  for  10,  15, 
20  and  25  cc.,  in  which  the  required  soap  solution  has  been  deter- 
mined, a  curve  for  the  strength  of  the  soap  solution  is  developed 
as  illustrated  in  the  chart,  Fig.  48. 

The  hardness  of  a  water  is  due  to  any  mineral  constituents  in 
solution  other  than  compounds  of  sodium,  potassium,  ammo- 
nium, etc.,  members  of  the  first  or  soluble  group.  Upon  the  addi- 
tion of  soap  to  a  hard  water  there  are  formed  insoluble  soaps  of 
calcium,  magnesium  and  iron,  which  are  precipitated  in  curdy 
granules.  When  all  of  these  constituents  are  precipitated  the 
water  is  soft.  It  is  this  action  of  soap  which  permits  of  its  use  in 
a  standard  solution  for  measuring  the  total  hardness. 

EXERCISE  V 

Determination  of  Calcium  Sulphate  in  Water. — Get  a  bottle  of 
unknown  A  for  analysis.  Add  25  *cc.  to^a  clean  beaker  with 

N 
a  pipette,  then  run  in  10  cc.  of  ^Q  sodium  carbonate  solution. 

Boil  for  5  min.  on  a  sand  bath,  then  filter  into  a  clean  beaker. 
Wash  well  with  hot  water,  saving  all  the  washings  until  the 
liquid  leaving  the  funnel  is  neutral  to  litmus  paper.  Now  add  2 
drops  of  methyl  orange  to  the  filtrate  and  washings  and  titrate 

N 
with  TQ  hydrochloric  acid. 

The  equation  representing  the  reaction  between  sodium  car- 
bonate and  calcium  sulphate  is 

CaS04  +  Na2C03  =  CaC03  +  Na2S04 

Since  the  titrated  sodium  carbonate  is  the  balance  of  the  10  cc. 
remaining  unchanged  after  the  reaction  has  taken  place,  the 
difference  between  this  amount  and  the  10  cc.  originally  added 


ANALYSIS  OF  BOILER  WATERS  211 

represents  the  amount  of  sodium  carbonate  taking  part  in  the 
reaction,  and  from  this,  remembering  always  the  equivalent 
of  normal  solutions,  compute  the  weight  of  calcium  sulphate 
present.  Since  a  25  cc.  sample  was  taken,  how  many  grams  per 
liter  did  the  solution  contain?  How  many  parts  per  million? 
How  many  grains  per  U.  S.  Gallon?1 

Calculate  also  the  lime,  in  grains  per  gallon,  equivalent  to  the 
calcium  sulphate  present.  Calculate  also  the  equivalent  of  cal- 
cium carbonate  in  grains  per  gallon  corresponding  to  the  sulphate 
ion  present.  From  the  amount  of  hydrochloric  acid  used,  calcu- 
late the  sodium  chloride  (NaCl)  formed. 

2HC1  +  Na2CO3  =  2NaCl  +  CO2  +  H20 

Perform  all  these  calculations  in  the  note  book  for  inspection 
and  reference. 

EXEBCISE  VI- 

Excess  or  Free  Carbon  Dioxide. — By  this  is  meant  the  carbon 
dioxide  held  in  solution  by  the  water.  It  is  not  scale  forming 
material,  but  in  water  treatment  it  behaves  as  so  much  temporary 
hardness,  and  the  amount  present  must  be  determined  in  order 
to  gage  correctly  the  quantity  of  reagent  required  in  the  treat- 
ment. The  " excess"  carbon  dioxide  is  readily  taken  up  by 
calcium  hydroxide,  Ca(OH)2,  forming  calcium  carbonate;  or  by 
sodium  carbonate,  forming  sodium  bicarbonate.  So  long  as  there 
is  present  free  carbon  dioxide,  it  acts  toward  phenolphthalein  as 
acid,  decolorizing  the  same.  The  first  excess  of  Na2C03  beyond 
the  point  of  absorption  of  the  CO2  is  denoted  by  a  pink  coloration 
of  the  indicator. 

Procedure. — With  the  graduated  cylinder  measure  200  cc.  of 
the  water  into  a  No.  3  (350-cc.)  beaker.  Add  a  few  drops  of 
phenolphthalein  as  indicator  and  titrate  to  the  end  point  with 

N 

,-Q  sodium  carbonate  free  from  bicarbonate.     The  number  of 

cubic  centimeters  used  times  5  represents  the  equivalent  or 
excess  of  C02  in  parts  per  million,  but  measured  in  terms  of 
calcium  carbonate. 

1  Milligrams  per  liter  or  part  per  million  X  0.0583  =  grains  per  U.  S. 
gallon.  See  p.  122. 


212  FUEL,  GAS,  WATER  AND  LUBRICATION 

EXERCISE  VII 

Total  Alkalinity  and  Temporary  Hardness. — Temporary 
hardness  is  due  to  the  calcium,  magnesium,  and  iron  held  in 
solution  in  the  form  of  bicarbonates.  They  are  readily  broken 
down  by  dilute  acids  and,  until  so  destroyed,  are  alkaline  towards 
methyl  orange  indicator. 

Procedure. — Measure  200  cc.  of  the  water  into  a  No.  3  beaker, 

N 
add  a  few  drops  of  methyl  orange  and  titrate  with  y~  sulphuric 

acid.  From  the  number  of  cubic  centimeters  used  can  be  calcu- 
lated the  equivalent  in  parts  per  million  of  temporary  hardness 
measured  in  terms  of  calcium  carbonate.  Note  that  to  calculate 
the  value  in  cubic  centimeters  per  liter  we  would  need  to  multiply 

N 
the  titration  by  five.     The  equivalent  value  for  ^  sulphuric  acid 

in  terms  of  calcium  carbonate  is  0.005  gram  per  cubic  centimeter 
of  solution.  Hence,  five  times  the  number  of  cubic  centimeters 
per  liter  would  represent  the  calcium  carbonate  in  milligrams 
per  liter.  That  is,  25  times  the  titration  number  represents 
milligrams  per  liter  or  parts  per  million  of  calcium  carbonate 
equivalent. 

NOTE. — If  under  Exercise  X  below  sodium  carbonate  is  found 
to  be  present  as  negative  hardness,  the  temporary  hardness  is 
equal  to  the  total  alkalinity  minus  the  negative  hardness.  If 
there  is  no  negative  hardness  the  temporary  hardness  is  equal 
to  the  total  alkalinity. 

EXERCISE  VIII 

Magnesia. — Use  the  solution  from  Exercise  VII  above.  Cover 
the  beaker  with  a  watch  glass,  boil  for  15  min.,  add  50  cc.  of 
saturated  lime  water  and  allow  to  stand  at  near  the  boiling 
temperature  for  about  15  min.  Filter  into  a  250-cc.  flask,  wash 
with  boiled  distilled  water  and  add  water  so  that  the  volume  at 

N 
room  temperature  will  be  250  cc.     Titrate  100  cc.  with  ^  sulphuric 

acid,  using  the  methyl  orange  indicator.  Make  at  the  same 
time  the  same  determination,  using  pure  distilled  water  in  place 
of  the  water  analyzed.  The  difference  between  the  two  titra- 
tions  is*the  amount  of  sulphuric  acid  which  would  have  been  neu- 


ANALYSIS  OF  BOILER  WATERS  213 

tralized  by  the  calcium  hydroxide,  which  has  precipitated  the 
magnesium  from  the  water.  Since  the  amount  titrated,  100  cc., 
is  equal  to  two-fifths  of  the  250  cc.,  it  must  also  be  equal  to  two- 
fifths  of  the  original  200  cc.  Then  the  difference  between  the 
titrations  multiplied  by  (f )  5  X  5  equals  the  equivalent  in  parts 
per  million  of  the  magnesia  in  the  water  measured  in  terms  of 
calcium  carbonate. 

NOTE. — Because  of  the  solubility  of  magnesium  carbonate  in 
the  presence  of  alkali  bicarbonates,  it  is  necessary  to  precipi- 
tate the  magnesium  as  hydroxide.  In  water  treatment,  therefore, 
the  magnesium  bicarbonate  requires  double  the  amount  necessary 
to  simply  bring  it  to  the  carbonate  stage  (see  p.  125,  Part  I). 

EXERCISE  IX 

Permanent  Hardness. — Boil  in  a  porcelain  dish  500  cc.  of  the 

N 
water  for  about  10  min.  and  add  25  cc.  of  —    "soda  reagent" 

(equal  parts  of  sodium  hydroxide  and  sodium  carbonate)  and 
boil  further  to  about  J  volume.  Filter,  wash  and  make  up  to 

N 
250  cc.     Titrate  100  cc.  of  this  solution  with  y~  sulphuric  acid, 

using  methyl  orange  as  an  indicator.  The  amount  of  original 
water  used  is  then  200  cc.  since  the  100  cc.  used  is  two-fifths  of 
the  250  cc.  and  consequently  two-fifths  of  the  500  cc.  The 
difference  between  this  titration  and  the  amount  of  acid  equiva- 

N 

lent  to  10  cc.  y^  soda  reagent  multiplied  by  (5  X  5)  represents 

the  equivalent  of  permanent  hardness  in  parts  per  million  meas- 
ured in  terms  of  calcium  carbonate.  Calculate  also  the  amount 
in  parts  per  million  of  the  sodium  sulphate  formed  by  the  reaction 
and  refer  the  result  for  use  under  Exercise  XIV. 

In  the  reaction,  as  with  "soda  reagent"  for  example 

CaSO4    +    Na2CO3(25  cc.)    = 

Na2SO4  +  CaC03  +  Na2C03  (25  -  z)cc., 

N 
it  is  seen  that  part  of  the  y^  sodium  carbonate  has  changed  over 

to  sodium  sulphate.  The  extent  of  this  change  is  dependent,  of 
course,  upon  the  quantity  of  calcium  sulphate,  magnesium  sul- 


214  FUEL,  GAS,  WATER  AND  LUBRICATION 

phate,  etc.,  present  in  the  water  and  the  measure  of  the  change  is 
indicated  by  the  titration  of  the  filtrate.  It  is  to  be  noted  again 
that  in  so  far  as  magnesium  sulphate  may  be  present,  the  mag- 
nesium carbonate  formed  is  soluble  to  a  considerable  extent, 
hence  the  more  insoluble  magnesium  hydroxide  is  provided  for 
by  the  use  of  the  "soda  reagent,"  which  is  part  sodium  hydroxide. 
Some  waters  will  give  a  titration  in  the  filtrate  which  is  greater 
in  amount  than  the  quantity  of  soda  reagent  added.  This 
condition  is  designated  as  negative  hardness. 

EXERCISE  X 

Negative  Hardness. — Throughout  the  drift  region  of  the 
Mississippi  Valley  a  very  large  percentage,  especially  of  the  deep 
wells,  yield  waters  of  Class  I,  as  described  on  page  119.  Such 
waters  have  no  sulphates  of  calcium  or  magnesium  present.  They 
have,  however,  some  free  sodium  bicarbonate  instead,  which 
indicates  that  some  such  reaction  as  indicated  in  Exercise  IX 
above  has  taken  place  while  the  water  was  percolating  through 
the  ground.  The  treatment,  therefore,  prescribed  above  would 
result  simply  in  the  addition  of  more  alkali.  Hence,  the  excess 
of  acid  required  over  the  10  cc.  of  alkali  added  would  be  a  meas- 
ure of  the  free  sodium  carbonate  or  "negative  hardness"  present. 
Multiplying  by  (5  X  5.3)  would  give  the  weight  in  milligrams 
per  liter  of  Na2C03.  Calculate  the  negative  hardness  in  terms 
of  calcium  carbonate  in  order  to  obtain  the  temporary  hardness. 

EXERCISE  XI 

Total  Hardness. — The  total  hardness  of  a  water  may  be 
derived  (a)  from  the  data  which  has  resulted  from  Exercises 
VII  and  IX  above,  and  (6)  from  the  soap  test.  It  is  well  to  use 
both  sources  of  information  as  a  check. 

(a)  Under  Exercise  VII  there  will  be  measured  the  amount  of 
temporary  or  bicarbonate  hardness;  that  is,  the  amount  of 
calcium,  magnesium  and  iron  present  as  bicarbonates,  but  meas- 
ured all  together  in  terms  of  calcium  carbonate  by  the  titration 

N 
with  JQ  hydrochloric  acid  or  sulphuric  acid. 

Under  Exercise  IX  there  will  be  indicated   the   amount   of 


ANALYSIS  OF  BOILER  WATERS 


215 


sulphate  or  chloride  hardness;  that  is,  the  amount  of  calcium, 
magnesium  or  iron  which  may  be  present  in  the  form  of  the 
sulphates  or  chlorides  of  these  elements,  but  measured  again 
in  the  equivalent  of  calcium  carbonate.  Be  sure  that  Exercise 
X  has  been  taken  into  this  account,  for,  if  free  sodium  bicar- 


100 


90 


70 


50 


34567 
Cubic  Centimeters  Soap  Solution 

FIG.  49. — Plotting  a  curve  for  standard  soap  solution,  showing  the  value  in 
parts  per  million  of  CaCOa. 

bonate  is  present,  there  will  be  no  permanent  but  only  temporary 
hardness  to  enter  into  the  total  hardness.  The  sum  of  the 
temporary  hardness  and  permanent  hardness  (if  any),  given  in 
terms  of  calcium  carbonate,  represents  the  total  hardness. 

(6)  Make  a  determination  of  total  hardness  by  means  of  the 
standard  soap  solution  as  follows: 

Measure  50  cc.  of  the  water  into  a  No.  3  beaker,  add  a  few 

N 
drops  of  methyl  orange  and  titrate  with    ~  sulphuric  acid  to  the 


216  FUEL,  GAS,  WATER  AND  LUBRICATION 

end  point.  Transfer  the  water  thus  neutralized  to  the  shaking 
bottle  used  for  the  soap  test  and  run  in  from  a  burette,  the  stand- 
ard soap  solution,  a  few  tenths  of  a  cubic  centimeter  at  a  time, 
shaking  vigorously  after  each  addition.  The  end  point  is  taken 
in  the  same  manner  by  noting  where,  upon  laying  the  bottle 
on  its  side  after  shaking,  the  lather  remains  for  5  min.  With 
waters  containing  magnesium  salts  care  must  be  taken  to 
avoid  mistaking  the  salts  of  magnesium  end  point.  After  the 
titration  is  apparently  finished  read  the  burette  and  add  5  cc. 
of  soap  solution.  If  the  end  point  was  due  to  magnesium  the 
lather  disappears.  Continue  the  addition  of  soap  solution  until 
the  true  end  point  is  reached. 

Upon  the  page  of  dimension  paper  herewith,  locate  a  curve 
which  represents  the  strength  of  the  soap  solution  used  and  from 
this  read  the  amount  of  parts  per  million  in  terms  of  calcium 
carbonate.  How  does  the  amount  compare  with  the  total 
hardness  as  derived  under  (a)  above? 

EXERCISE  XII 

Determination  of  Total  Sulphates. — Into  a  100-cc,  cylinder 
measure  50  cc.  of  water  and  add  25  cc.  of  sodium  chloride  solu- 
tion as  on  page  207.  Make  up  to  exactly  100  cc.  in  the  graduated 
cylinder.  Pour  into  an  Erlenmeyer  flask  of  about  200  cc.  capac- 
ity and  add  special  barium  chloride  as  in  Exercise  III  for  the 
determination  of  sulphuric  acid.  After  standing  5  to  20  min., 
read  in  the  photometer  as  directed  in  Chapter  XXII,  pages 
174  to  178. 

Refer  to  the  chart  on  page  176  for  the  weight  of  sulphur  indica- 
ted by  the  photometer  reading.  Calculate  to  sulphuric  acid  thus 
32  : 142  : :  weight  of  S  :  Na2S04 

EXERCISE  XIII 

Determination  of  Total  Chlorides. — Measure  accurately  50  cc. 
of  water  by  means  of  a  50-cc.  pipette  into  a  porcelain  dish.  Add 

N 
about  1  cc.  of  potassium  chromate  solution  and  titrate  with  JQQ 

silver  nitrate  solution,  until  the  yellow  color  gives  place  to  the 
first  permanent  trace  of  reddish-brown.  Do  not  wait  for  a  red 
tint  to  appear.  Fill  another  porcelain  dish  with  50  cc.  of  dis- 


ANALYSIS  OF  BOILER  WATERS  217 

tilled  water  and  add  1  cc.  of  the  indicator.  Use  this  as  a  stand- 
ard of  comparison.  The  first  tinge  of  brownish-red  that  can  be 
distinguished  in  the  titrated  solution  is  to  be  taken  as  the  end 
point. 

The  reactions  involved  are 

2AgN03  +  K2Cr04  =  2KN03  +  Ag2Cr04 

The  silver  chromate  is  a  red  precipitate,  but  as  long  as  there  is 
any  soluble  chloride  in  solution,  this  breaks  up  the  chromate  as 
follows : 

Ag2Cr04  +  CaCl2  =  2AgCl  +  CaCr04 

Thus,  the  first  permanent  tinge  of  pink  shows  that  the  chlorine  of 
the  chloride  has  all  been  precipitated.  From  the  volume  of 
silver  nitrate  used  to  this  point,  calculate  the  weight  of  chlorine 
in  the  50  cc.  taken  thus 

N 
volume  JQQ  AgN03  X  0.0003545  =  weight  Cl  in  50  cc. 

N 
and  0.0005845  X  the  volume  irkn  AgNO3  =  weight  NaCl  inSOcc. 

1UU 

of  the  water.  Multiplying  further  by  20  will  give  the  weight 
per  liter.  From  this  is  indicated,  by  referring  to  milligrams,  the 

milligrams  per  liter  or  parts  per  million. 

• 

EXERCISE  XIV 

Total  Alkalies. — The  total  alkalies  are  considered  as  being 
made  up  of  all  the  sulfate  not  combined  as  permanent  hardness 
and  all  of  the  chlorides.  It  is  true  that  small  amounts  of  other 
alkali  salts,  as  sodium  nitrate,  are  present  and  occasionally  some 
of  the  chloride  is  present  as  magnesium  or  calcium  chloride;  but, 
for  the  scope  of  this  work  and  for  ordinary  technical  requirements, 
it  is  quite  sufficient  to  consider  the  total  alkalies  as  being  con- 
stituted as  above  indicated. 

Procedure. — From  the  total  sulphate  as  determined  under  XII 
and  calculated  to  sodium  sulphate,  subtract  the  sulphate  hardness 
as  found  under  IX  and  which  was  there  calculated  also  to  the 
equivalent  of  sodium  sulphate  for  this  purpose.  The  remainder 
is  the  amount  of  alkalies  existing  in  the  water  in  the  form  of 
sodium  sulphate.  To  the  above  should  be  added  the  total 
chloride  results  under  XIII,  calculated  to  sodium  chloride. 


218  FUEL,  GAS,  WATER  AND  LUBRICATION 

If  free  sodium  carbonate  or  negative  hardness  was  developed 
under  X  then  this  also  in  the  form  of  equivalent  sodium  carbon- 
ate should  be  added  as  a  third  constituent  of  the  alkalies. 

The  sum  of  these  various  constituents,  referred  in  each  instance 
to  parts  per  million,  is  to  be  taken  as  the  total  alkalies  in  parts 
per  million.  Calculate  this  sum  also  to  grains  per  U.  S.  gallon. 

EXERCISE  XV 

Examination  of  a  Treated  Water. — 1.  If  the  water  has  been 
under  treated,  it  is  possible  to  determine  as  with  an  untreated 
water  the  amounts  of  lime  and  soda  still  needed  to  soften  water. 

2.  In  case  excess  of  soda  ash  has  been  added,  the  permanent 
hardness  will  be  negative;  and,  if  the  water  has  no  sodium  car- 
bonate present   originally,   1.06  times  the    negative  hardness 
expressed  as  parts  per  million  of  calcium  carbonate  represents 
the  excess  of  sodium  carbonate  which  has  been  added  to  the  water. 

3.  In  most  cases,  however,  a  treated  water  is  alkaline  to 

N 

phenolphthalein,  in  which  case  200  cc.  is  titrated  with  y^  sul- 
phuric acid,  to  the  end  point  with  phenolphthalein  and  then  on 
to  the  end  point  with  methyl  orange. 

If  the  amount  of  acid  needed  to  give  the  end  point  with  the 
phenolphthalein  is  more  than  half  that  which  is  needed  to  give 
the  end  point  with  methyl  orange,  an  excess  of  lime  is  present.  If 
the  difference  between  the  two  quantities  be  subtracted  from 
the  number  of  cubic  centimeters  for  the  phenolphthalein  end 
point,  the  result  shows  the  calcium  carbonate  equivalent  in 
parts  per  million  of  the  excess  of  pure  lime,  CaO.  This  equiva- 
lent multiplied  by  56  gives  the  parts  per  million  of  CaO  and 
this  result  multiplied  by  0.0583  gives  the  amount  in  pounds  per 
1,000  gal. 

EXERCISE  XVI 

Summary  of  Results  and  Calculations. — The  character  of  a 
water  is  shown  by  assembling  in  tabular  form  the  various  in- 
gredients grouped  in  a  manner  to  indicate  the  total  scale-forming 
and  the  total  foaming  ingredients,  as  called  for  in  the  accompany- 
ing outline.  This  summary  calls  for  the  various  results  in  grains 
per  gallon,  and  the  order  and  grouping  is  that  of  the  Exercises 
VI  to  XV. 


ANALYSIS  OF  BOILER  WATERS  219 

The  calculations  for  the  requisite  amount  of  reagents  to  remove 
the  scaling  ingredients  involve  simply  the  calculation  from  the 
determined  equivalent  of  calcium  carbonate  over  to  the  proper 
reacting  substance,  thus: 

Since  one  equivalent  of  excess  C02,  one  equivalent  of  tempo- 
rary hardness  or  one  equivalent  of  magnesium  requires  one 
equivalent  of  calcium  oxide  for  its  removal  from  the  water,  0.56 
times  the  sum  of  the  calcium  carbonate  equivalent  of  excess 
carbon  dioxide,  temporary  hardness,  and  magnesium  represents 
the  number  of  parts  per  million  of  pure  lime  CaO,  necessary  to 
remove  these  impurities. 

One  and  six  hundredths  times  the  calcium  carbonate  equivalent 
of  the  permanent  hardness  is  the  number  of  parts  per  million  of 
sodium  carbonate,  Na2C03,  necessary  to  remove  the  permanent 
hardness;  0.0583  times  the  quantities  in  parts  per  million  X 
T  gives  the  pounds  per  thousand  gallons  needed.  The  results 
above  are  for  pure  lime  and  sodium  carbonate.  Commercial 
lime  and  soda  ash  must  be  analyzed  to  determine  the  amounts  of 
pure  lime  and  sodium  carbonate  which  they  contain. 

TABLE  XXII.  —  SHOWING  THE  RATIO  OF  REAGENT  TO  INCRUSTING  MATERIAL 
REQUIRED  FOR  WATER  TREATMENT 

Weight  of  1  U.  S.  gallon  of  water  at  65°F  ...............................    58,330  grains 

1  part  :  1,000,000  :  :  x  :  58,330 
Hence,  x  grains  per  gallon  =  0.05833  X  parts  per  million. 

1  part  free  CO2          requires  1  .  27  parts  CaO  and  leaves  no  foaming  material 

1  part  NaaCOs          requires  0  .  53  part   CaO  and  leaves  1  part  foaming  material 

1  part  CaCOs            requires  0  .  36  part    CaO  and  leaves  no  part  foaming  material 

1  part  CaSO4             requires  0  .  78  part    Na2COs  and  leaves  1  .  04  parts  foaming  material 

1  part  CaCh              requires  0  .  96  part    Na2COs  and  leaves  1  .  05  parts  foaming  material 

1  part  MgCOs           requires  1  .  33  parts  CaO  and  leaves  no  part  foaming  material 

1  part  MgSO4            requires  0  .  88  part    NazCOs    -f  and  leaves  1  .  18  parts  foaming  material 

0.47  part  CaO 

1  part  MgCh            requires  1.11  parts  Na2COs   +  and  leaves  1  .  22  parts  foaming  material 

0.59  part  CaO 

1  part  acid  (H^SOO  requires  0  .  57  parts  CaO  +  1.08  and  leaves  1  .  45  parts  foaming  material 

parts 


NOTE.  —  As  an  aid  to  calculations  and  a  correct  designation  of  the  kind  of  alkalinity  present 
the  following  table  will  be  found  helpful: 

Letting  Pt  stand  for  the  titration  when  using  phenolphthalein  and  Mo  for  the  titration 
when  using  methyl-orange,  then  — 

When  Pt  —        Mo  there  are  present  hydroxides  only. 

When  Pt  <        Mo  >   £  Mo  there  are  present  hydroxides  and  normal  carbonates. 
When  Pt  =    J    Mo  there  are  present  normal  carbonates  only. 

When  Pt  <    2    Mo  there  are  present  normal  carbonates  and  acid  carbonates. 

When  Pt  =        Mo  there  are  present  acid  carbonates  only. 


220 


FUEL,  GAS,  WATER  AND  LUBRICATION 


SUGGESTED  FORM  FOB  REPORTING  RESULTS  OBTAINED  IN  THE 

PRECEDING  EXERCISES 
Analysis  of  Boiler  Water  from 


No 


Sample  Taken 192, 


Free  CO2  as  CaCO3  equivalent  
Total  alkalinity  as  CaCO3  equivalent 
Temporary   hardness   as   CaCO3 

Requiring  for 
treatment  of 
1,000  gal. 

Grains 
per 
gallon 

Parts 
per 
million 

Pounds 
of 
slaked 
lime 

Pounds 
of  99.0 
per  cent 
soda  ash 

Negative  hardness  as  CaCO3  equiva- 
lent 

Magnesium  as  CaCO3  equivalent  

Permanent   hardness   as   CaCO3 
equivalent  

x    (| 

Total  scale  forming  material  

Alkalies  as  Na2S04 

Alkalies  as  NaCl 

Alkalies  as  Na2CO3  

Remarks , 


By 


CHAPTER  XXVII 


OIL  EXAMINATION 

Specific  Gravity.  —  The  specific  gravity  of  oils  may  be  taken 
with  a  hydrometer,  Westphal  balance  or  pyknometer.  The 
Beaume  hydrometer  is  the  instrument  commonly  used  in  connec- 
tion with  industrial  oil  work.  Such  readings  may  be  changed  to 
specific  gravity  by  reference  to  a  conversion  table  (Appendix, 
Table  X)  or  by  application  of  the  formula  published  by  the 
Bureau  of  Standards: 

140    • 
Sp.  gr.  60°/60°F. 


The  Westphal  balance,  Fig.  50, 
for  light  and  medium  oils  is  recom  - 
mended  because  it  combines  in 
a  satisfactory  manner  both  con- 
venience and  accuracy.  It  is 
provided  with  a  beam  graduated 
by  notches  into  10  equal  parts. 
With  the  plummet  attached  in 
air,  the  pointer  should  stand  at 
zero.  The  heaviest  weight 
placed  on  the  hook  at  the  end  of 
the  beam,  that  is  when  located 
at  what  would  be  equivalent  to 
the  tenth  notch,  will  exactly 
counterbalance  the  plummet 
when  suspended  in  distilled  water 
at  60°F.  The  pointer  should 
swing  equal  distances  above  and 
below  the  zero  point  or  come  to 

a  rest  at  zero  when  adjusting  the  balance  with  the  plummet  in  water. 
The  other  three  weights  are  respectively  equal  to  TV,  iiir  and  r^Vir 
of  the  weight  of  the  largest  one,  hence,  their  positions  on  the  beam 
give  readings  directly  in  the  four  decimal  places.  In  testing  a  liquid 
the  plummet  should  be  immersed  so  that  on  the  upward  swing 

221 


FIG.  50.— Westphal  balance. 


222 


FUEL,  GAS,  WATER  AND  LUBRICATION 


it  will  not  come  above  the  liquid.  The  temperature  of  the 
liquid  should  be  carefully  taken  and  if  different  from  60°F.,  the 
specific  gravity  reading  should  be  corrected  to  that  temperature. 
The  reading  of  the  weights  is  taken  from  their  positions  on 
the  beam  in  the  order  of  their  size.  For  example,  if  the  heaviest 
weight  is  at  7,  the  next  at  4,  the  third  at  9,  and  the  smallest  at  2, 
the  specific  gravity  reading  is  0.7492. 

If  the  oil  is  thick,  it  should  be  warmed  to  allow 
free  movement  of  the  float.  The  temperature 
must  then  be  read  and  corrected  for.  See  table 
of  specific  gravities  for  oils  and  corrections  for 
temperature,  Tables  XI  and  XIV  of  the  Appen- 
dix. This  would  apply  also  where  the  hydrome- 
ter is  the  apparatus  used. 

For  oils  and  tars  too  heavy  for  the  Westphal 
balance  and  for  pitches  which  must  be  softened 
for  pouring,  the  pyknometer  method  is  advis- 
able. A  special  form  of  instrument  of  the 
Hubbard  type  is  recommended.1  The  main 

FlG  51 sped-  features  of  this  pyknometer,   Fig.   51,   are  its 

fie  gravity  bottle,  straight  sides  making  it  easy  to  clean,  and  a  stop- 
per with  a  large  capillary,  1.6  mm.  bore,  with  a 
concave  space  on  its  lower  surface  to  facilitate  the  escape  of  air 
bubbles.  The  weight  of  the  clean,  dry  apparatus  a  is  obtained, 
also  the  weight  b  of  the  apparatus  full  of  recently  boiled  distilled 
water  cooled  to  25°C.  These  values  are  constants  and  need  to  be 
determined  but  once.  The  weight  of  the  pyknometer  full  of 
oil  c  at  25°C.  will  then  give  the  necessary  data  for  the  specific 
gravity,  thus: 


c  —  a 


=  specific  gravity  of  the  oil 


Of  course  for  very  heavy  material  such  as  pitch  where  it  is 
desired  to  only  partially  fill  the  receptacle  with  the  sample,  the 
pyknometer  method  is  still  applicable.  The  pitch  is  melted 
and  a  portion  poured  into  the  apparatus  being  careful  to  avoid 

1  HUBBARD,  PREVOST,  A  useful  form  of  pyknometer  for  determining  the 
specific  gravity  of  semi-solid  bitumens:  Jour.  Ind.  Eng.  Chem.,  vol.  1,  p. 
475,  1909. 


OIL  EXAMINATION 


223 


smearing  the  sides.  The  weight  of  the  apparatus  thus  partially 
filled  and  brought  to  room  temperature  is  designated  as  d. 
Then  by  completing  the  filling  with  water  we  have  the  weight 
e  hence: 

77 ^ -/- -Tr  =  specific  gravity  of  the  sample  taken 

(6  —  a)  —  (e  —  a) 

Flash  and  Fire  Test. — The  Cleveland  open-cup  tester,  Fig.  52, 
is  very  well  suited  for  determining  the  flash  point 
of  lubricating  oils.  It  has  been  adopted  as  the 
standard  by  the  American  Society  for  Testing 
Materials.  Readings  are  from  5  to  15°  lower 
than  the  Pensky-Martens  closed  tester  which  is 
very  widely  used  as  a  standard.1 

The  metal  holding  about  100  cc.  is  supported 
in  a  tripod  ring  and  heated  directly  without  sand 
bath  or  outer  cup.  It  should  have  a  mark  J  in. 
below  the  top  and  another  f  in.  below  the  first, 
the  latter  to  be  used  with  oils  flashing  above 
425°F. 

A  thermometer  is  suspended  in  the  oil  midway 
between  the  center  and  the  inside  edge  of  the 
cup.  The  bulb  should  be  within  J  in.  of  the 
bottom  and  entirely  submerged  in  the  oil.  The 
bulb  for  this  purpose  should  be  not  over  f  to  f 
in.  in  length. 

Heat  by  a  direct  flame,  rapidly  at  first,  but 
slower  as  the  flash  point  is  approached,  when  a 
test  is  made  for  every  5°F.  rise  in"  temperature. 
The  flame  for  testing  is  supplied  from  a  glass 
capillary  and  should  be  a  small  bead-like  flame 
not  exceeding  f  in.  in  length.  It  is  passed  slowly 
across  the  center  of  the  cup  J  in.  above  the  sur-  CUP,  flash  and  fire 
face  of  the  oil,  and  occupying  1  sec.  in  the  passage.  l 

The  temperature  when  a  flame  first  jumps  from  the  test 
flame  to  the  oil  is  called  the  flash  point.  A  subdued  light  and 
freedom  from  drafts  are  essential  to  satisfactory  observations. 

1  The  Am.  Soc.  Testing  Mat.  (Committee  D-21)  has  made  the  Tagliabue 
instrument  the  standard  for  obtaining  the  flash  and  fire  point  by  the  closed 
tester  method. 


FIG  . 
Cleveland, 


224 


FUEL,  GAS,  WATER  AND  LUBRICATION 


After  the  flash  point  has  been  obtained  the  fire  point  is  found 
by  continuing  the  heat  till  a  flame  is  produced  which  continues 
to  burn.  This  temperature  is  designated  as  the  fire  point. 

Viscosity. — The  specific  viscosity  of  a  liquid  is  the  time  taken 
for  a  given  quantity  to  flow  through  an  orifice  as  compared 


.Sectional  View  of 
Standard  Oil  Tube.  Receiving  Flask. 

FIG.  53. — Essential  features  of  the  Saybolt  standard  universal  viscosimeter. 

with  water,  at  a  given  temperature.  A  pipette  graduated  to 
deliver  100  cc.  of  water  from  the  bulb  alone,  that  is,  not  including 
the  lower  stem,  in  34  sec.  is  the  simplest  form  of  apparatus  for 
such  a  purpose.  In  oil  work  an  arbitrary  factor  is  obtained 
which  varies  with  the  type  of  instrument  employed,  hence  the 


OIL  EXAMINATION  22*5 

viscosity  number  and  the  name  of  the  instrument  by  which  it  was 
determined  must  be  coupled  together.  The  Engler  viscosimeter 
is  standard  with  the  Teutonic  and  Scandinavian  countries  and 
has  been  adopted  by  the  International  Society  for  Testing 
Materials,  while  in  England  the  Redwood  instrument  is  the 
standard.  The  American  Society  for  Testing  Materials  pre- 
scribes (1921  " Standards")  that  "  Viscosity  shall  be  determined 
by  means  of  the  Saybolt  Standard  Universal  Viscosimeter." 
The  most  essential  parts,  omitting  the  external  jacketing  bath, 
are  shown  in  Fig.  53.  There  is  a  standard  oil  tube,  A,  fitted  at 
the  top  with  an  overflow  cup,  B.  The  tube  is  a  small  outlet  of 
definite  shape  and  dimension.  The  lower  end  of  the  larger 
tube  is  closed  by  a  cork  forming  an  air  chamber  which  prevents 
the  oil  from  flowing  through  the  standard  outlet  orifice  till  the 
cork  is  removed.  The  receiving  flask  has  a  capacity  at  the 
mark  of  60  cc. 

Viscosity  numbers  may  be  determined  at  100,  130  or  210°F. 
The  temperature  of  the  oil  in  the  standard  tube  is  held  con- 
stant by  means  of  the  surrounding  bath  which  is  preferably 
of  oil. 

To  make  a  test,  heat  the  oil  bath  to  the  desired  tempera- 
ture and  clean  out  the  oil  receptacle,  pouring  some  of  the  oil 
to  be  tested  through  the  tube  and  allowing  it  to  drain  out  below. 
Especial  care  must  be  taken  that  no  sediment  or  lint  is  allowed 
to  enter  the  standard  tube. 

After  inserting  the  stopper  at  the  lower  end  of  the  air  chamber, 
fill  the  standard  tube  with  the  oil  to  be  tested.  It  will  save  time 
to  have  it  already  heated  to  near  the  point  desired  before  adding 
it  to  the  tester.  Oil  should  be  added  until  it  ceases  to  overflow 
into  the  cup  at  B. 

Both  the  bath  and  the  oil  sample  should  be  well  stirred. 
When  equilibrium  at  the  desired  temperature  has  been  estab- 
lished, remove  the  thermometer  or  stirrer  from  the  sample  and 
by  means  of  a  pipette  withdraw  'the  oil  from  the  overflow  cup 
until  the  level  is  below  the  overflow  edge  at  B.  Place  the  60-cc. 
flask  in  position,  quickly  remove  the  cork  and  at  the  same  instant 
start  the  stop  watch.  Stir  the  liquid  in  the  outer  bath,  main- 
taining the  proper  temperature  and  stop  the  watch  when  the 
bottom  of  the  meniscus  reaches  the  mark. 

15 


226  FUEL,  GAS,  WATER  AND  LUBRICATION 

The  time  in  seconds  for  the  delivery  of  the  60  cc.  is  the  Saybolt 
Universal  viscosity  number  of  the  oil  at  the  designated  tempera- 
ture of  the  test. 

Free  Acid. — Lubricating  oils  should  be  free  from  sulphuric  acid 
used  in  refining  and  free  also  from  sulphonates  resulting  from 
treatment  with  acid  for  the  removal  of  unsaturated  hydro- 
carbons. Fatty  acids  from  the  oils  used  in  compounding  if 
present  in  small  amount  are  not  so  objectionable. 

Weigh  10  grams  of  oil  into  an  Erlenmeyer  flask  and  add  50  cc. 
of  ethyl  alcohol  which  has  had  2  or  3  drops  of  phenolphthalein 

N 
added  and  brought  to  a  very  faint  pink  with  j~  potassium 

hydroxide  solution.     Heat  to  boiling  and  agitate  well.     Titrate 

N 
the  hot  solution  with  ^  KOH  solution. 

Calculate  the  number  of  milligrams  of  potassium  hydroxide 
required  to  neutralize  the  free  acids  present  per  gram  of  oil. 
This  is  the  acidity  number. 

Saponification  Number. — The  fatty  oil  may  be  determined  by 
effecting  a  complete  saponifi cation  with  a  known  amount  of 
standardized  alcoholic  potash  solution  and  titrating  the  unused 
potash.  The  solution  is  made  by  dissolving  33  grams  of  stick 
KOH  in  1,000  cc.  of  purified  95  per  cent  ethyl  alcohol. 

Weigh  10  grams  of  oil  into  a  350  cc.  Erlenmeyer  flask  and  add 
from  a  burette  50  cc.  of  the  alcoholic  potash  solution  and  25  cc. 
of  purified  or  c.p.  benzene,  C6H6.  Boil  with  a  reflux  condenser 
of  sufficient  length  and  proper  regulation  of  heat  so  as  to  avoid 
loss  of  the  volatile  material.  Continue  the  boiling  for  45  min. 
and  add  25  cc.  of  neutral  gasoline.  Add  2  or  3  drops  of  phe- 

N 
nolphthalein  and  titrate  with  -^  HC1  until  the  pink  color  is 

z 

destroyed.  Titrate  as  a  blank  an  equivalent  amount  of  alcoholic 
potash  solution  and  purified  benzene  as  used  in  the  saponification 
process.  Calculate  the  number  of  milligrams  of  potassium 
hydroxide  required  to  saponify  1  gram  of  the  oil.  This  is  the 
saponification  number.1  For  example,  each  cubic  centimeter  of 
i  GILL'S  "Oil  Analysis,"  5th  ed.,  p.  65. 


OIL  EXAMINATION  227 

N 

2  HC1  is  equivalent  to  0.02805  gram  KOH.     Hence, 

No.  cc.|  acid  X  0.02805  _    ,          s  RQK  per  gram  of  ^ 


Wt.  of  oil  taken  ( taken,  or  saponification  No. 

For  the  common  fatty  oils  used  in  compounding,  the  average 
saponification  number  is  195,  that  is,  for  every  0.195  gram  of 
KOH  there  is  1  gram  of  fatty  oil  present  in  the  mixture,  hence 
the  percentage  of  such  an  oil  is  found  by  introducing  this  factor 
into  the  above  equation  and  multiplying  by  100,  thus: 

No.  cc.  f  acid  X  0.02805  ^    r  pep  cent  Q£  f fttty 
Wt.  of  oil  taken  X  0.195  "    j  oil  in  the  mixture. 

Maumene  Test. — Weigh  into  a  beaker  50  grams  of  oil.  The 
beaker  should  be  jacketed  or  so  arranged  as  to  avoid  loss  of  heat 
by  radiation.  Take  the  temperature  of  the  oil  and  retain  the 
thermometer  in  the  oil  as  a  stirrer.  Add  from  a  burette  with 
constant  stirring  drop  by  drop,  10  cc.  of  concentrated  sulphuric 
acid  and  note  the  highest  temperature.  Subtract  the  tempera- 
ture of  the  oil  at  the  start.  The  rise  in  temperature  in  degrees 
Centigrade  is  the  Maumene  number.  Consult  the  Table  XIV, 
in  the  Appendix  for  possible  interpretation  of  the  results.  It 
should  be  noted  that  the  percentage  of  saponifiable  material  in 
the  oil  must  enter  into  the  conclusion  as  to  the  type  of  fatty  oil 
employed  in  compounding. 

The  Conradson  Test. 1 — Ten  cubic  centimeters  of  oil  is  weighed 
into  a  25  cc.  porcelain  crucible  which  is  placed  inside  of  a  Skid- 
more  iron  crucible  approximately  55  mm.  in  diameter  by  35  mm. 
high,  with  one  hole  in  the  cover  left  open.  Place  these  two 
inside  of  a  second  iron  crucible  approximately  80  mm.  in  diameter 
by  70  mm.  high  having  also  a  cover.  Arrange  on  a  tripod  and 
cover  with  a  hood  or  inverted  assay  crucible  in  such  a  manner 
that  the  heat  will  be  distributed  evenly  on  all  sides. 
^  Heat  from  a  Meker  burner  using  a  large  flame  at  first  which 
will  envelop  the  large  crucible.  When  vapors  from  the  oil 
start  to  ignite  above  the  crucible  reduce  the  flame  so  that  the 
vapors  will  come  off  at  a  uniform  rate  burning  at  a  height  of 

1  Am.  Soc.  for  Testing  Mat.,  "Standards,"  p.  701,  1921. 


228 


FUEL,  GAS,  WATER  AND  LUBRICATION 


about  5  cm.  above  the  large  crucible.  After  the  vapors  cease, 
increase  the  heat  as  at  first  and  continue  for  5  min.  The 
bottom  of  the  large  crucible  should  be  red  hot.  Allow  the  tem- 
perature to  reduce  before  opening,  remove  the  porcelain  crucible 
to  a  desiccator,  cool  and  weigh.  Approximately  |  hr.  will  be 
required  for  the  process  when  properly  regulated.  The  deposit 
as  percentage  of  the  original  sample  is  designated  as  carbon 
residue,  from  the  Conradson  test. 

T~ 
%  * 

<Vi 

^ — 

le- 


<r 


< -f'Picf. > 

6  fo7  Sqrucrre 

Y. Jjf  "Pier.  Hols  -  -  ->j 


FIG.  54. — Conradson  carbon-residue  apparatus. 

Emulsification. — The  emulsification  test  as  adopted  by  the 
Am.  Soc.  Testing  Mat.,1  may  be  summarized  as  follows: 

Twenty  cubic  centimeters  of  oil  and  40  cc.  of  distilled  water 
are  placed  in  a  100-cc.  graduated  cylinder  of  approximately 
1  in.  inside  diameter,  and  heated  in  a  water  bath  at  130°F.  A 
mechanical  stirrer  is  then  introduced  for  5  min.  It  should  have 
an  r.p.m.  of  1,500  and  the  paddle  should  be  entirely  submerged. 

1  Am.  Soc.  for  Testing  Mat.,  Technical  Papers,  Part  II,  p.  248,  1916. 


OIL  EXAMINATION  229 

The  suggested  size  of  the  paddle  is  3J  by  ^f  by  T^  in.  attached 
with  its  longest  dimension  in  line  with  the  driving  shaft.  After 
stirring,  the  mixture  is  allowed  to  stand  in  the  bath  at  130°F. 
At  convenient  intervals,  readings  are  taken  of  the  volume  of 
clear  oil  which  settles  out  noting  the  point  of  separation  in  line 
with  the  upper  surface  of  the  meniscus. 

Calculate  the  rate  of  demulsification  in  cubic  centimeters 
per  hour.  Note  that  the  average  rate  is  taken.  That  is  if  D 
is  the  total  volume  demulsified  at  any  stage  and  t  the  time  in 
minutes  from  the  cessation  of  stirring,  then 

— —  =  rate  of  demulsification  per  hour. 

It  is  to  be  observed  that  the  cylinder  readings  are  from  the 
bottom  up,  and  that  D  in  the  above  expression  is  60  minus  the 
upper  surface  reading  of  the  emulsion.  Hence  if  the  reading  at 
the  end  of  1  min.  is  40,  then  the  demulsified  portion  X  60  = 
1,200,  or  the  rate  of  demulsification  per  hour.  This  would  be 
the  highest  possible  demulsibility.  If  the  readings  showed  10 
cc.  demulsified  at  the  end  of  15  min.,  the  rate  would  be  j$  X 
60  =  40  cc.  per  hour.  A  complete  table  for  time  and  readings 
from  59  to  40  is  a  convenience.1 

>  See  Table  III,  Am.  Soc.  for  Testing  Mat.,  Part  II,  p.  258,  1920. 


APPENDIX 
TABLE  I. — INTERNATIONAL  ATOMIC  WEIGHTS  (1921) 


Symbol 

Atomic 
weight 

Symbol 

Atomic 
weight 

Al 

27  1 

Molybdenum  

Mo 

96.0 

Sb 

120  2 

Neodymium  

Nd 

144.3 

A 

39  9 

Ne 

20.2 

As 

74  96 

Nickel 

Ni 

58  68 

Ba 

137  37 

Niton  (radium  emana- 

Bi 

208  0 

tion 

Nt 

222  4 

B 

10  9 

Nitrogen  

N 

14.008 

Br 

79  92 

Osmium  

Os 

190.9 

Cd 

112  40 

Oxygen                  

o 

16  0 

Cs 

132.81 

Palladium  

Pd 

106.7 

Ca 

40.07 

Phosphorus  

P 

31.04 

c 

12.005 

Platinum  

Pt 

195.2 

Ce 

140.25 

Potassium  

K 

39.1 

Chlorine              

Cl 

35.46 

Praseodymium  

Pr 

140.9 

Cr 

52.0 

Radium  

Ra 

226.0 

Cobalt               

Co 

58.97 

Rhodium  

Rh 

102.9 

Columbium  

Cb 

93.1 

Rubidium  

Rb 

85.45 

Cu 

63  57 

Ruthenium  

Ru 

101.7 

Dv 

162  5 

Samarium  

Sa 

150.4 

Er 

167  7 

Scandium  

Sc 

45.1 

Eu 

152  0 

Se 

79.2 

F 

19  0 

Si 

28.3 

Gd 

157  3 

Silver  

Ag 

107  .  88 

Gallium 

Ga 

70  1 

Na 

23.0 

Ge 

72  5 

Sr 

87.63 

Gl 

9  1 

s 

32.06 

Gold 

Au 

197  2 

Tantalum  

Ta 

181.5 

He 

4  0 

Tellurium  

Te 

127.5 

Ho 

163  5 

Terbium     

Tb 

159.2 

H 

1  008 

Thallium  

Tl 

204.0 

In 

114  8 

Thorium  

Th 

232.15 

j 

126  92 

Thulium  

Tm 

168.5 

I  'di 

Ir 

193  1 

Tin  

Sn 

118.7 

Fe 

55  84 

Ti 

48.1 

Kr 

82  92 

Tungsten  

W 

184.0 

yp 

T  a 

Uranium  

U 

238.2 

v 

51.0 

Lead  

Pb 

207.2 

Xenon               

Xe 

130.2 

Li 

6.94 

Lutecium  

Lu 

175.0 

Ytterbium    (Neoytter- 

hiiim^ 

Yb 

173  5 

Mg 

24.32 

Yttrium 

Yt 

89  33 

Manganese  

Mn 

54.93 

Zinc 

Zn 

65  37 

Hg 

200.6 

Zr 

90.6 

230 


APPENDIX  231 

TABLE  II. — MISCELLANEOUS  CONVERSION  FACTORS 
Lengths 

1  in.    =  2 . 54  cm.  1  mm.  =  0 . 03937  in. 

1  ft.    =  0.3048  m.  1  cm.    =  0.3937  in. 

1  yd.  =  0.9144m.  1m.      =3. 28  ft. 

1  mi.  =  1.62137  km.  1  km.    =  0.62137  mi. 

Volumes 

1  cu.  in.    =  16.382  cu.  cm.  1  cu.  cm.  =    0.61  cu.  in. 

1  cu.  ft.    =    0.02832  cu.  cm.  1  liter        =  61.02327  cu.  in. 

1  cu.  yd.  =    0.7658cu.  cm.  1  cu.  m.     =     1.3279cu.  yd. 

Capacities 

1  qt.    =  0.94636  liters  1  liter  =  1.05668  qt. 

1  gal.  =  3.78543  liters  1  liter  =  0.26417  gal. 

Masses 

1  oz.  av.  =    28 . 3495  grams  1  gram  =  0 . 03527  oz. 

1  Ib.  av.  =  453 . 95  grams  1  kilo     =  2 . 20462  Ib. 

1  gram  15.43235  grains 

1  oz.  =        437 . 5  grains 

lib.  =    7, 000.0  grains 

1  U.  S.  gallon  =  58,278.0  grains 

1  Imp.  gallon  =  70,000.0  grains 

Heat  Values 

IB.t.u.  =  251.99cal. 

leal.  =      0. 003968  B.t.u. 

1  B.t.u.  per  pound  =      0.5556  Cal.  per  gram 

1  cal.  per  gram        =      1.8  B.t.u. 's  per  pound 

lB.t.u.  =  0.252  Cal. 

1  Cal.  =  3. 968  B.t.u. 

1  B.t.u.  per  pound  =  0 . 5556  Cal.  per  kilo 

1  Cal.  per  kilo          =  1.8  B.t.u. 's  per  pound 


232 


FUEL,  GAS,  WATER  AND  LUBRICATION 


TABLE  III. — CONVERSION  TABLES  FOR  TEMPERATURES 
Centigrade  to  Fahrenheit 


Tempera- 
ture, degrees 
Centigrade 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

0 

32.0 

33.8 

35.6 

37.4 

39.2 

41.0 

42.8 

44.6 

46.4 

48.2 

10 

50.0 

51.8 

53.6 

55.4 

57.2 

59.0 

60.8 

62.6 

64.4 

66.2 

20 

68.0 

69.8 

71.6 

73.4 

75.2 

77.0 

78.8 

80.6 

82.4 

84.2 

30 

86.0 

87.8 

89.6 

91.4 

93.2 

95.0 

96.8 

98.6 

100.4 

102.2 

40 

104.0 

105.8 

107.6 

109.4 

111.2 

113.0 

114.8 

116.6 

118.4 

120.2 

50 

122.0 

123.8 

125.6 

127.4 

129.2 

131.0 

132.8 

134.6 

136.6 

138.2 

60 

140.0 

141.8 

143.6 

145.4 

147.2 

149.0 

150.8 

152.6 

154.4 

156.2 

70 

158.0 

159.8 

161.6 

163.4 

165.2 

176.0 

168.8 

170.6 

172.4 

174.2 

80 

176.0 

177.8 

179.6 

181.4 

183.2 

185.0 

186.8 

188.6 

190.4 

192.2 

90 

194.0 

195.81197.6 

199.4 

201.2 

203.0 

204.8 

206.6 

208.4 

210.2 

100 

212.0 

213.8 

215.6 

217.4 

219.2 

221.0 

222.8 

224.6 

226.4 

228.2 

APPENDIX 


233 


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234 


FUEL,  GAS,  WATER  AND  LUBRICATION 


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APPENDIX 


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236  FUEL,  GAS,  WATER  AND  LUBRICATION 

TABLE  V. — RELATIVE  HUMIDITY 

As  determined  from  readings  of  wet  and  dry  bulb  thermometer.   Calculated 

for  barometric  pressure  of  29.0  in.  of  mercury 

All  temperatures  in  Fahrenheit  degrees 


Depression  of  wet  bulb  thermometer  (t  —  t') 

Air 

temperature 

,1 

3 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

30 

80 

78 

68 

57 

47 

37 

27 

17 

8 

35 

91 

82 

73 

64 

55 

46 

37 

29 

20 

12 

4 

40 

92 

84 

76 

68 

61 

53 

46 

38 

31 

23 

16 

9 

2 

45 

93 

86 

79 

71 

65 

58 

52 

45 

39 

33 

26 

20 

14 

8 

2 

50 

93 

87 

81 

74 

68 

62 

56 

50 

44 

39 

33 

28 

22 

17 

12 

7 

2 

55 

94 

88 

82 

76 

71 

65 

60 

55 

49 

44 

39 

34 

29 

25 

20 

15 

11 

6 

2 

60 

94 

89 

84 

78 

73 

68 

63 

58 

53 

49 

44 

40 

35 

31 

27 

22 

18 

14 

10 

e 

2 

65 

95 

90 

85 

80 

75 

70 

66 

62 

57 

53 

48 

44 

40 

36 

32 

28 

25 

21 

17 

13 

10 

7 

3 

70 

95 

90 

86 

81 

77 

72 

68 

64 

60 

56 

52 

48 

44 

40 

37 

33 

30 

26 

23 

20 

17 

13 

10 

7 

4 

75 

96 

91 

87 

82 

78 

74 

70 

66 

63 

59 

55 

51 

48 

44 

41 

38 

34 

31 

28 

25 

22 

19 

16  13 

11 

80 

96 

91 

87 

83 

79 

76 

72 

68 

64 

61 

5754 

51 

47 

44 

41 

38 

35 

32 

29 

27 

24 

21  18 

16 

85 

96 

92 

88 

84 

80 

77 

74 

70 

66 

63 

6057 

54 

50 

47 

44 

41 

39 

36 

33 

31 

28 

25 

23 

20 

90 

96 

92 

89 

85 

81 

78 

75 

71 

68 

65 

6259 

56 

53 

50 

47 

44 

42 

39 

37 

34 

32 

29 

27 

24 

95 

96 

93 

89 

86 

82 

79 

76 

73 

70 

66 

6461 

58 

55 

52 

50 

47 

45 

42 

40 

37 

35 

32 

30 

28 

100 

96 

93 

90 

86 

83 

80 

77 

74 

71 

68 

65 

62 

59 

57 

54 

52 

49 

47 

44 

42 

40 

37 

35 

33 

31 

APPENDIX 


237 


TABLE  VI. — CORRECTIONS,  IN  BRITISH  THERMAL  UNITS,  TO  BE  APPLIED  TO 

OBSERVED  HEATING  VALUES  IN  CALCULATING  TOTAL  HEATING 

VALUES  OF  ILLUMINATING  GAS 

(About  600  B.t.u.)1 

The  tabular  corrections  are  applicable  when  inlet  water,  air,  gas,  and 
products  are  all  at  approximately  the  same  temperature,  and  when  the 
calorimeter  is  operated  at  normal  rate  of  gas  consumption. 


Relative  humidity  of  air 

Temperature 
of  room, 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

etc.  degrees 

per 

per 

per 

per 

per 

per 

per 

per 

per 

per 

Fahrenheit 

cent 

cent 

cent 

cent 

cent 

cent 

cent 

cent 

cent 

cent 

40 

+  2 

+  2 

+  1 

+1 

+1 

+1 

0 

0 

0 

_ 

45 

+  2 

+  2 

+  2 

+1 

+1 

+1 

0 

0 

0 

— 

50 

+  3 

+  3 

+  2 

+2 

+1 

+1 

-o 

0 

0 

— 

55 

+  3 

+  3 

+  3 

+2 

+1 

+1 

+1 

0 

0 

— 

60 

+  4 

+  4 

+  3 

+2 

+2 

+1 

+1 

0 

0 

— 

65 

+  5 

+  4 

+  4 

+3 

+2 

+2 

+1 

0 

-1 

— 

70 

+  6 

+  5 

+  4 

+3 

+3 

+2 

+1 

0 

-1 

-2 

75 

+  7 

+  6 

+  5 

+4 

+3 

+2 

+1 

0 

-1 

-2 

80 

+  8 

+  7 

+  6 

+5 

+4 

+3 

+1 

0 

-1 

-2 

85 

+10 

+  9 

+  7 

+6 

+4 

+3 

+2 

0 

-1 

-3 

90 

+12 

+10 

+  9 

+7 

+5 

+4 

+2 

0 

-2 

-3 

95 

+14 

+12 

+10 

+8 

+6 

+4 

+2 

0 

-2 

-4 

U.  S    Bureau  of  Standards.     Technologic  Paper  36. 


238 


FUEL,  GAS,  WATER  AND  LUBRICATION 


TABLE  VII.1 — EMERGENT  STEM  CORRECTIONS  TO  READING  OF  OUTLET- 
WATER  THERMOMETERS  FOR  DIFFERENT  IMMERSIONS  OF 
THERMOMETERS  IN  CALORIMETER  FOR  DETERMINING 

HEATING  VALUE  OF  GAS 

Table  applicable  when  temperature  of  inlet  water  is  approximately  equal 
to  room  temperature. 


Tempera- 

ture 

Temperature  of  room 

rise  of 

water, 

degrees 

Fahren- 

50° 

60° 

70° 

80° 

90° 

100° 

heit 

10 

+0.02 

+0.03 

+0.04 

+0.05 

+0.05 

+0.06 

Thermometer  immersed  to  30°F.  .  . 

15 

+0.04 

+0.05 

+0.06 

+0.07 

+0.09 

+0.10 

20 

+0.06 

+0.07 

+0.09 

+0.11 

+0.13 

+0.15 

10 

+0.01 

+0,02 

+0.03 

+0.03 

+0.04 

+0.05 

Thermometer  immersed  to  40°F.  .  . 

15 

+0.03 

+0.04 

+0.05 

+0.06 

+0.08 

+0.09 

20 

+0.04 

+0.05 

+0.07 

+0.09 

+0.11 

+0.12 

10 

+0.01 

+0.01 

+0.02 

+0.03 

+0.04 

+0.05 

Thermometer  immersed  to  50°F  .  .  . 

15 

+0.02 

+0.03 

+0.04 

+0.05 

+0.07 

+0.08 

20 

+0.02 

+0.04 

+0.06 

+0.07 

+0.09 

+0.11 

10 

+0.00 

+0.01 

+0.02 

+0.02 

+0.03 

+0.04 

Thermometer  immersed  to  60°F  .  .  . 

15 

+0.00 

+0.01 

+0.03 

+0.04 

+0.05 

+0.06 

20 

+0.00 

+0.02 

+0.04 

+0.05 

+0.07 

+0.09 

This  table  is  not  applicable  if  the  emergent  portion  of  the  stem  includes 
an  enlargement  in  the  capillary. 

Instead  of  using  the  above  table,  it  will  probably  be  somewhat  more  con- 
venient to  make  out  a  stem-correction  table  for  the  particular  outlet-water 
thermometer  that  is  to  be  used  with  the  calorimeter,  the  data  for  this 
separate  stem-correction  table  being  interpolated  from  the  above  table. 

Suppose,  for  example,  the  outlet-water  thermometer  to  be  used  was  one 
that  was  immersed  to  the  30°F.  mark  on  the  scale,  and  a  stem-correction 
table  were  wanted  for  an  18°F.  rise  in  temperature,  then  from  the  above 
table  we  obtain  the  following  stem-correction  table : 

STEM  CORRECTION  FOR  OUTLET-WATER  THERMOMETER  No. — 
Table  applicable  when  inlet  water  is  approximately  at  room  temperature, 
when  thermometer  is  immersed  to  the  30°F.  mark,  and  when  the  tempera- 
ture rise  is  approximately  18°F. 


Inlet-water 
temperature, 
degrees  Fahrenheit 

Stem 
correction, 
degree 

Inlet-water 
temperature, 
degrees  Fahrenheit 

Stem  correc- 
tion, degree 

50 
60 
70 

0.05 
0.06 
0.08 

80 
90 
100 

0.09 
0.11 
0.13 

1  From  U.  S.  Bureau  of  Standards,  Circular  48. 


APPENDIX 


239 


TABLE  VIII. — SOLUBILITIES  APPLICABLE  TO  BOILER  WATERS 
(a)  Solubility  of  gypsum 

(CaS04.2H20) 

1  part  dissolves  in  about  [500  parts  of  water  at  60°F. 
1  part  dissolves  in  about  1,200  parts  of  water  at  250°F. 
1  part  dissolves  in  about  1,800  parts  of  water  at  300°F. 
1  part  dissolves  in  about  3,800  parts  of  water  at  325°F. 

(&)  Solubility  of  lime  and  hydrated  lime 

(CaO  and  Ca(OH)2) 

Amount  required  to  saturate  one  U.  S.  gallon 
78  grains  CaO  or  103.0  grains  Ca(OH)2  at  60°F. 
70  grains  CaO  or  92.5  grains  Ca (OH) 2  at  86°F. 
58  grains  CaO  or  76.6  grains  Ca(OH)2  at  112°F. 
51  grains  CaO  or  67.4  grains  Ca(OH)2  at  140°F. 
33  grains  CaO  or  43.6  grains  Ca(OH)2  at  212°F. 


TABLE   IX.1 — EQUIVALENT  OP   DEGREES   BAUME    (AMERICAN   STANDARD) 
AND  SPECIFIC  GRAVITY  AT  60°F.  (HEAVIER  THAN  WATER) 


Degrees 
Baume 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

0 

1.0000 

1.0069 

1.0140 

1.0211 

1.0284 

1.0357 

1.0432 

.0507 

1.0584 

1.0662 

10 

1.0741 

1.0821 

1.0902 

1.0985 

1  .  1069 

1.1154 

1  .  1240 

.1328 

1.1417 

1  .  1508 

20 

1  .  1600 

1.1694 

.1789 

1.1885 

1.1983 

1.2083 

1.2185 

.2288 

1.2393 

1.2500 

30 

1  .  2609 

1.2719 

.2832 

1  .  2946 

1.3063 

1.3182 

1.3303 

.3426 

1.3551 

1.3679 

40 

1.3810 

1  .  3924 

.4078 

1.4216 

1.4356 

1  .  4500 

1.4646 

.4796 

1.4948 

1.5104 

50 

1  .  5263 

1  .  5426 

.5591 

1.5761 

1  .  5934 

1.6111 

1  .  6292 

.6477 

1.6667 

1.6860 

60 

1.7059 

1.7262 

.7470 

1.7683 

1.7901 

1.8125 

1.8354 

.8590 

1.8831 

1.9079 

For  more  complete  table  see  VAN  NOSTRAND'S  "  Chemical  Annual. 


240 


FUEL,  GAS,  WATER  AND  LUBRICATION 


TABLE  X.1 — CONVERSION  TABLE  FOE  DEGREES  BAUM£   (LIGHTER  THAN 
WATER)  TO  SPECIFIC  GRAVITY  AND  POUNDS  PER  GALLON 


Degrees 
Baume" 

Specific 
gravity 

Pounds 
in  1  gal. 
(American) 

Degrees 
Baume" 

Specific 
gravity 

Pounds 
in  1  gal. 
(American) 

1 

10 

1.0000 

8.33 

43 

0.8092 

6.74 

0.9929 

8.27 

44 

0.8045 

6.70 

0.9859 

8.21 

45 

0.8000 

6.66 

13J 

0.9790 

8.16 

46 

0.7954 

6.63 

14 

0.9722 

8.10 

47 

0.7909 

6.59 

15 

0.9655 

8.04 

48 

0.7865 

6.55 

16 

0.9589 

7.99 

49 

0.7800 

6.52 

17 

0.9523 

7.93 

50 

0.7777 

6.4? 

18 

0.9459 

7.88 

51 

0.7734 

6.44 

19 

0  9395 

7.83 

52 

0.7692 

6.41 

20 

0.9333 

7.78 

53 

0.7650 

6.37 

21 

0.9271 

7.72 

54 

0.7608 

6.34 

22 

0.9210 

7.67 

55 

0.7567 

6.30 

23 

0.9150 

7.62 

56 

0.7526 

6.27 

24 

0.9090 

7.57 

57 

0.7486 

6.24 

25 

0.9032 

7.53 

58 

0.7446 

6.20 

26 

0.8974 

7.48 

59 

0.7407 

6.17 

27 

0.8917 

7.43 

60 

0.7368 

6.14 

28 

0.8860 

7.38 

61 

0.7329 

6.11 

29 

0.8805 

7.34 

62 

0.7290 

6.07 

30 

0.8750 

7.29 

63 

0.7253 

6.04 

31 

0.8695 

7.24 

64 

0.7216 

6.01 

32 

0.8641 

7.20 

65 

0.7179 

5.98 

33 

0.8588 

7.15 

66 

0.7142 

5.95 

34 

0.8536 

7.11 

67 

0.7106 

5.92 

35 

0.8484 

7.07 

68 

0.7070 

5.89 

36 

0.8433 

7.03 

69 

0.7035 

5.86 

37 

0.8383 

6.98 

70 

0.7000 

5.83 

38 

0.8333 

6.94 

75 

0.6829 

5.69 

39 

0.8284 

6.90 

80 

0.6666 

5.55 

40 

0.8235 

6.86 

85 

0.6511 

5.42 

41 

0.8187 

6.82 

90 

0.6363 

5.30 

42 

0.8139 

6.78 

95 

0.6222 

5.18 

Specific  gravity  X  10  =  pounds  per  Imperial  gallon. 

1  For  more  complete  table,  see  VAN  NOSTRAND'S  "Chemical  Annual." 


APPENDIX 


241 


TABLE  XI. — TABLE  FOB  CALCULATING  THE  SPECIFIC  GRAVITY  OF  OILS  AT 

15.5°C. 
Example:   A  =  sp.  gr.  at  20°     A  X  1.00319  =  sp.  gr.  at  15.5°C. 


Temperature, 
degrees  Centi- 
grade 

Factor 

Tempera- 
ture, degrees 
Centigrade 

Factor 

Tempera- 
ture, degrees 
Centigrade 

Factor 

Tempera- 
ture, degrees 
Centigrade 

Factor 

10 

0.99612 

14 

0.99894 

18 

1.00177 

22 

1.00462 

11 

0.99683 

15 

0.99965 

19 

1.09248 

23 

1.00534 

12 

0.99782 

16 

1.00935 

20 

1.00319 

24 

1.00605 

13 

0.99823 

17 

1.00106 

21 

1.00391 

25 

1.00677 

WRIGHT,  C.  H.,  Jour.  Soc.  Chem.  Ind.,  26,  513. 


TABLE  XII. — REPRESENTATIVE  SAMPLES  OF  LUBRICATING  OILS 

By  ALBERT  F.  SEEKER, 
From  "Van  Nostrand's  Chemical  Annual" 


Name 

Sp.  gr., 
60  deg- 
rees 
Fahren- 
heit 

Flash 
test, 
degrees 
Fahren- 
heit 

Fire 
test, 
degrees 
Fahren- 
heit 

Cold 
test, 
degrees 
Fahren- 
heit 

Saponi- 
fiable 
matter 

Ash 

Acidity 
or  alka- 
linity 

Air  compressor  oil  
Air  compressor  oil  
Car  oil  

0.8857 
0.8654 
0  8824 

455 
410 
354 

525 
460 
400 

25 
-2 
5 

trace 
none 
none 

none 
none 
none 

neutral 
neutral 
neutral 

Cutting  oil  

0  9036 

345 

425 

31 

82.9  % 

none 

1.16  % 

Cylinder  oil  

0.8921 

535 

600 

60 

20.0  % 

trace 

neutral 

Cylinder  oil  

0.9020 

545 

600 

31 

2.4  % 

none 

neutral 

Cylinder  oil  
Cylinder  oil  

0.8993 
0.8992 
0  9163 

590 
555 
430 

600 
600 
480 

27 

none 
none 
1  5  % 

0.06% 
0.08% 

neutral 
neutral 

Engine  oil  .  ... 

0  8845 

360 

415 

5 

10  0  % 

none 

0  05  % 

Engine  oil  

0  8970 

400 

465 

3 

none 

none 

Engine  oil  

0.8810 

405 

470 

14 

none 

0  02  % 

neutral 

150  degrees  fire  test  oil 
150  degrees  fire  test  oil 
High-speed  engine  oil. 
High-speed  engine  oil. 
Ice  machine  oil  

0.7864 
0.8206 
0.9152 
0.9149 
0  8941 

140 
266 
400 
400 
430 

180 
300 
465 
475 
495 

32 
5 
3 

—4 

none 
none 
17.2% 
15.3% 
none 

none 
none 
0.06% 
0.04% 
0  13  % 

neutral 
neutral 
1.09% 
1.06% 

Machine  oil  

0  8689 

420 

480 

o 

trace 

none 

neutral 

Marine  engine  oil  
Marine  engine  oil  
Marine  engine  oil  
Marine  engine  oil  
Screw  cutting  oil  
Transformer  oil  

0.8812 
0.8765 
0.9090 
0.9054 
0.9002 
0.8646 

405 
435 
405 
400 
380 
365 

440 
500 
464 
470 
425 
430 

17 
5 
0 
9 
15 
2 

none 
none 
12.0% 
9.0% 
25.0% 
none 

trace 
0.05% 
0.15% 
0.11% 
none 
none 

neutral 
neutral 
0.75% 
0.50% 
1.02% 
neutral 

242 


FUEL,  GAS,  WATER  AND  LUBRICATION 


TABLE  XIII. — MAUMENE  TEST,  SHOWING  THE  RISE  IN  TEMPERATURE  OP 

COMMON  OILS 
From  "Stillman's  Engineering  Chemistry,"  4th  edition 


Lard  oil  

Name  of  observer 

Maumene' 

Schaedler 

Archbutt 

Allen 

Stillman 

Degrees 
Centigrade 
40 
41-43 
45 

Degrees 
Centigrade 

Degrees 
Centigrade 

Degrees 
Centigrade 
41 

Degrees 
Centigrade 
39.5 
39 
40 
37 
38 
48 
92 
128 
80 
110 
74 
60 
45 
42 
10       . 
3 

65 

85 

Tallow  oil  

Neat's  foot  oil  

50 

43 
37* 

51 
92 
123-128 

70 

'sir 

45-47 
91 
126 

Oleo  oil  

Elain  oil  

Sperm  oil  

103 
69.5 

Whale  oil 

102-103 

58 
47 
42 

Cod  liver  oil 

113 
67-69 

Crude  cotton  seed  oil  
Rape  oil 

Castor  oil 

48 
43 
28 

46 
41-45 

65 
41-43 
18-22 
3-4 

Olive  oil 

Rosin  oil 

Mineral  lubricating  oil 

Earth  nut 

67 

67 

47-60 

Sea  elephant 

Corn  oil 

APPENDIX 


243 


TABLE  XIV. — PHYSICAL  FACTORS  FOR  THE  MORE  COMMON  OILS 
Average  values 


Oils 

Specific 
gravity 

Degrees 
BaumS 

Pounds 
per 
gallon 

Maumene 
number 

Iodine 
number 

Saponifi- 
cation 
number 

Castor                            .  * 

0  9640 

15  2 

8  03 

46  5 

86  0 

181  5 

0  9115 

23  6 

7  59 

21  0 

10  0 

257  0 

Cod  liver 

0  9245 

21  4 

7  70 

107  5 

152  0 

185  5 

0  9232 

21  6 

7  69 

80  0 

121  0 

190  5 

Cotton  seed         

0  9235 

21  6 

7  69 

66  0 

110  5 

193  0 

0  9267 

21  1 

7  72 

97  0 

154  0 

192  5 

Lard                         

0  9160 

22  8 

7  63 

43  5 

72  5 

196  5 

Linseed                 

0  9345 

19  8 

7  78 

115  0 

186  0 

192  5 

Menhaden            

0  9300 

20  5 

7  75 

126  0 

156  0 

191  0 

Neat's  foot              

0  9153 

23  0 

7  62 

53  0 

69  5 

194  5 

Olive                   

0  9160 

22  8 

7  63 

43  0 

79  0 

192  5 

Palm         

0.9340 

19  9 

7  78 

54  0 

200  5 

Peanut  

0.9165 

22.7 

7  63 

56  0 

94  0 

191  5 

Rape  seed  (Colsa) 

0  9150 

23  0 

7  62 

58  5 

98  5 

173  0 

0.9227 

21.7 

7.69 

65  0 

108  5 

190  5 

0.9265 

21.1 

7.72 

60  0 

130.0 

195.0 

0  8808 

29  0 

7  34 

85  0 

85  5 

135  0 

0  9249 

21  4 

7  70 

67  5 

127  0 

191  0 

Tung                                 . 

0  9395 

19  0 

7  83 

157  5 

193  5 

Whale                           .    . 

0  9240 

21  5 

7  69 

88  0 

119  0 

191  0 

Water 

1  0000 

10  0 

8  33 

Alcohol  (95  per  cent.)  .  .  .  . 

0.80854 

43.15 

6.735 

NOTE. — Specific  gravity,  Baume",  gravity  and  pounds  per  gallon  deter- 
mined at  60°F. 


INDEX 


Adiabatic  calorimeters,  41,  169 
Air  analysis,  202,  203 
Alcohol,  3,  87 

denatured,  88 

fuel  value,  88 

Alkalinity  of  water,  135 

total,  212 

Ammonia  in  gas,  94 
Analysis  of  air,  202,  203 
Analysis  of  coal,  25-30,  141-148 
ash,  29,  143,  144 
calculations,  27,  147 
fixed  carbon,  30,  147 
general  plan,  28 
laboratory  sample,  23,  141 
methods,  27 

moisture,  25,  28,  142,  143 
proximate,  141-148 
sulphur,  29,  76,  171 
volatile  matter,  30,  146 
working  sample,  23,  141 
Aquadag,  138 

Ash  and  water,  free  substance,  31 
Ash  in  coal,  29,  33,  62,  143 
corrected  ash,  29,  32 
determination,  143 
fusibility,  70 

penalties  for  excess,  63,  64 
variations,  16,  18 
Available  hydrogen,  49 


Boiler  waters  (see  Water),  112-136,. 

204-220 
British  thermal  unit,  defined,  36 


Calculations  from   air   dry   to   dry 
coal,  etc.,  27,  147 


Calculations  involving  unit  coal,  53 
commercial  guarantees,  60 
in  settlement  of  contracts,  60 
Calorie,  defined,  36 
Calorific  determinations,  149-170 
Berthier  test,  38 
correction  for  acids,  43 
corrections  for  fuse  wire,   45, 

155,  168 
definitions,    36 
oxygen     bomb     method,     39, 

161-170 
peroxide    bomb-   method,    45, 

149-160 
radiation  corrections,  40,   154, 

155,  167 

Calorific  values,  36 
anthracites,  156 
calculated  by  formula,  37,  101 
carbon,  37 

coal,  37,  56,  149-170 
coke,  156 
computations     in     connection 

with  oxygen  bomb,  167 
gas,  90-94,  196 

gross  and  net  heat  values,  47,  94 
wood,  83,  84 
Calorimeters,  38-48 
adiabatic,  41,  169 
continuous  flow  gas,  92,  197 
gas,  90-93,  197 
intermittent  gas,  91 
junker,  92,  197 
Lewis-Thompson,  38 
Mahler  bomb,  39 
oxygen  bomb,  39,  161-170 
Parr  non-continuous  gas,  91 
peroxide  bomb,  45,  149-160 
water  equivalent,  155,  167 
Carbon  dioxide  in  water,  211 
Carbon  in  coal,  49,  107,  179  K' 

method  of  determining,  179-183 
245 


246 


INDEX 


Centigrade,  conversion  to  Fahren- 
heit, 36 
Classification  of  coals,  51-58 

bibliography,  58 

Campbell's,  52 

carbon  ratio,  52 

carbon-hydrogen  ratio,  52 

Frazer's,  51 

fuel  ratio,  51 

heating  value  as  a  basis,  52 

unit  coal  as  a  basis,  53-58 
Classification  of  water,  119 

according  to   type  of   mineral 
constituent,  119 

as  used  by   the   C.    B.    &   Q 
Ry.,  131 

by  the  association  of  railway 

chemists,  116 
Cleveland  open  cup  flash  and  fire 

tester,  223 
Clinker  formation,  69 

cause,  70 

prevention,  70 
Coagulants,  125 
Coal,  2,  5 

analysis,  25-30 

classification,  51-58 

deterioration,  73 

distribution,  7,  9 

output,  5,  8 

production,  annual,  6 

production,  by  states,  8 

proximate  analysis,  141-148 

reserves,  7 

sampling,  11-24 

spontaneous  combustion,  73 

storage,  73-79 

weathering,  73 
Coal  contracts,  59-64 

bids  and  awards,  62 

double  standard  of  reference,  62 

formulation  of  proposals,  64 

penalties  for  ash,  63,  64 

price  and  payment,  64 

significance  of  heating  values,  62 

use  of  unit  coal,  heating  values, 
60 


Coke,  2,  80-82 

analysis,  81 

heating  value,  156 

metallurgical,  80 

pulverizing,  81 

sampling,  81 

sulphur,  82 

volatile  matter,  81 
Combustible,  31 
Combustion  of  coal,  65-72 

clinker  formation,  69 

efficiencies,  107-111 

losses  up  flue,  109 

other  losses,  110 

oxygen  supply,  66 

pounds   of    air   per   pound    of 
coal,  107 

ratio  of  entering  to  air  used,  108 

smoke,  67 

wetting  of  coal,  71 
Compositing  of  coal  samples,  19 
Compounded  oils,  138 
Conradson  test  on  oil,  140,  227 
Contracts  (see  Coal  contracts),  59 
Corrosive  ingredients  in  water,  119 

D 

Deterioration  of  coal,  73 
Distillates,  3,  86 

heating  values,  3,  87 

output,  86 
Dry  coal,  25 
Dulong's  formula,  37,  49 
Dust  determination,  23 

E 

Embrittling      action      of     alkaline 

waters,  135 
Emulsions  of  oil,  138 


Feldspar,  decomposition  of,  114 
Fixed  carbon,  30,  147 
determination,  147 


INDEX 


247 


Flash  and  fire  test,  139,  223 

Float  and  sink  coal,  table  of  heating 

values,  34 
Flue  gas,  104-111,  201-203 

analysis,  106,  203 

calculation    of    volumes     and 
weights,  107 

composition,  104,  108 

loss  of  heat,  109 

ratio  of  air  entering  to  air  used, 
108 

sampling,  106 

solutions  for  analysis,  201 
Foaming  ingredients,  117 
Fuel  (see  Coal). 


G 


Gas,  fuel,  3,  89-103 
ammonia,  94 
analysis;  95 .  185-200 
apparatus  for  analysis,  95,  185 
blast  furnace  gas,  90 
calorimeters,  90-94,  197 
computation     of     volume     of 

paraffins,  98 

combustion  temperatures,  97 
heating  value,  90,  196 
heating   value  by   calculation, 

101 
high  and  low  heating  values, 

94,  101,  102 
house  gas,  4,  90 
natural  gas,  4,  90 
producer  gas,  4,  90 
production,  89 
reagents  for  analysis,  95,  188 
sulphur,  94,  144 
types  of  gas,  89 
Gas  analysis,  95,  185-200 

absorption    methods,    95,    188, 

201 

combustion  methods,  97,  191 
errors,  100,  103,  193 
sulphur,  94,  189,  194 
Gas  calorimeter  corrections,  92,  94 
humidity,  236,  237 


Gas  inlet  water  temperature,  93 

thermometer  stem,  238 
Gasoline,  calorific  value,  87,  157 
Gross     and     net     heating    values, 

47,  94,  101 
Gypsum,  solubility,  115 


Hardness,  132,  213 

negative,  214 

permanent,  213 

total,  214 
Heating    value    of    coal,    37,    56, 

149-170 

Heating  value  of  gas,  90,  101 
Honeycomb     and     clinker    forma- 
tion,'70 

Hubbard  specific  gravity  bottle,  222 
Hydrogen  in  coal,  49,  184 

available,  49 

by  calculation,  49,  184 

Dulong's  formula,  37,  49 
Hydrogen  in  gas,  97,  191 
Hydrogen  sulphide  in  gas,  94,  189, 
194 


Illinois  coal,  composition,  56 

J 

Junker  calorimeter,  92,  197 

L 

Lime,  122,  124 

hydrated,  124 

impurity  allowed  for,  123 

solubility,  124 

use,  122 

use  in  water  treatment,  122 
Lubricants,  137-140 

analysis,  221-229 

Conradson  test,  140,  227 

emulsification,  140,  228 


248 


INDEX 


Lubricants,  flash  and  fire  test,  139, 

223 

free  acid  test,  140,  226 
Maumene  test,  227 
methods  for  testing,  221-229 
saponification  number,  140,  226 
specific  gravity,  139,  221 
viscosity,  139,  224 


Maumene'  test,  227 

Mineral  constituents  of  water,  112 

analysis,  204-219 

characteristics,  114 

source,  112 

Modified  Orsat  apparatus,  95-185 
Moisture  in  coal,  25,  77 

determination,  143 

interpretation  of  values,  28 

loss  on  air  drying,  142 

loss  in  sampling,  21 
Motion,  source,  1 


N 


Nitrogen  in  coal,  50 
Nomenclature    (referring    to    coal), 

25 

Non-coal,  32 
Normal  solutions,  204 


Permutit,  132 

Peroxide  calorimeter,  149-160 

accelerator,  151 

anthracites,  156 

calculations,  155 

charge,  151 

chemicals,  151 

coke,  156 

dismantling,  156 

gasoline,  157 

ignition,  153 

petroleum  oils,  157 

readings,  154 

sample,  150 

standardization,  159 
Petroleum,  3,  85 

distillates,  86 

heating  value,  3,  85,  157 

output,  85 
Power,  1 

Proximate  analysis,  141-148 
Pure  coal,  31 
Pyknometer,  221 
Pyrites  in  coal,  76 


R 


Radiation  corrections,  40,  154,  166 
oxygen  bomb,  40,  166 
peroxide  bomb,  154 

Riffling,  17 


Oildag,  138 

Oils  (see  Lubricants),  137-140 

animal,  137 

compounded,  138 

vegetable,  137 
Orsat  apparatus,  201 
Oxygen  bomb  calorimeter,  161-170 

adiabatic  insulation,  41,  169 

corrections,  43,  167 

manipulation,  163-167 

standardization,  169 
Oxygen  in  coal,  50,  184 


S 


Sampling  of  coal,  11-24 
amount  required,  12 
ash  variations,  16,  18 
car  lots,  18 
care,  11 

commercial  sampling,  11 
composite  samples,  19 
coning  and  quartering,  15 
dust  determinations,  23 
face  samples,  1 1 
grinder  used,  14 


INDEX  249 

Sampling,  hand  samples,  11  T 

laboratory  sample  23  Tagliabue   closed   cup    flash   point 
material  taken,  12  tester,  223 

mechamcal  samplmg,  20  Total  carbon 


J^g'    '  apparatus  for  measuring,  179 
moisture  control.  21  .     ,.        -~~ 

.ffl.  determination,  179 

Ln^'  table  for  weight  of  carbon,  182 

'cs'  /  use  of  carbon  values,  37,  108 
Saybolt     standard     universal     vis-      Treatment  of  boiler  water,  120-136 

cosimeter,  225  industrial  appliances,  128 
Scaling  ingredients,  115  ag  ^ 

effect.  116 

c,.  ,        ,  ;,  ,        f  tabulated  scheme,  121 

Sink  and  float  values  for  ash,  33 

Smoke,  67  -jj 

Smokeless  combustion,  66,  69 

Soda  ash  in  water  treatment,  124  Ultimate   analysis    of    coal,    49-50, 

Specifications    for    coal    (see    Coal  179-184 

contracts).  hydrogen  -  by    calculation,    49, 

Specific  gravity  of  oils,  221  184 

Spontaneous  combustion,  73  oxygen  bv  calculation,  184 
oxidation  stages,  73-78                     Unit  coal>  31~35 

Standard  solutions,  205-206  accuracy  of  constants,  33 

calcium  chloride,  208  calculation       of       commercial 

soap  solutions,  208-209  values,  60 

sodium  carbonate,  205  definitions,  31 

sulphuric  acid,  206  derivation  of  formula,  32 

Stokers  69  formula  for  calculating,  33 

Storage  of  coal,  73-79  formula  for  heating  values,  53 

deterioration,  73  heating  values,  56,  57 

iron  pyrites,  effect,  76  sink  and  float  values,  33 

methods,  78  use  in  classification,  53 

moisture,  influence,  77  use  in  contracts,  60 
oxidation     and     heat     stages,  y 

73-78 

spontaneous  combustion,  73  Volatile  matter  in  coal,  30,  146 

weathering,  73  official  method,  146 

Sulphur,  29,  171  optional  method,  146 
curve  for  photometer,  176                Volatile  fuels,  3,  86,  87 

in  coal,  29,  76,  171  heating     values     by      oxygen 
in  coke,  82  bomb,  87 

in  gas,  94,  189,  194  heating     values     by     peroxide 
photometer,  174-178  bomb,  157 

Sulphur  determination,  171-178 
Eschka  mixture  method,  172 

from  oxygen  bomb,  171  Water  for  industrial  use,  112-136 

from  peroxide  fusion,  172  alkalinity,  135,  212 

photometric,  174  analysis,  112,  204-219 


250 


INDEX 


Water,  artesian,  113 

calcium  sulphate,  210 
calculations,  218,  219 
carbon  dioxide,  211 
chemical  treatment,  120 
classification,  116,  119,  131 
coagulants,  125 
corrosive  ingredients,  119 
deep  wells,  113 
determination  of  sulphur,  207 
embrittling  action  (NaOH),  135 
foaming  ingredients,  117 
hardness,  212-214 
impurities,  115 
industrial  methods,  128 
lime  treatment,  122 
limits  of  purification,  132 
magnesia,  212 

mineral  constituents,  112,  114 
negative  hardness,  214 
permanent  hardness,  213 


Water,  scaling  ingredients,  115-116 

shallow  wells,  113 

soda  ash,  treatment,  124 

springs,  113 

standards  of  hardness,  132 

surface  water,  113 

temporary  hardness,  212 

total  alkalies,  217 

total  hardness,  214 

total  sulphates,  216 

treated  water,  examination  of, 
218 

typical  waters,  132 
Weathering  of  coal,  73 
Wet  coal,  25,  142 
Wetting  of  coal,  71 
Wood,  heating  value,  2,  83,  84 


Z 


Zeolites,  132 


NUMERAL  TECHNOLOGY  LIBRARY 
UNIVERSITY  OF  CALIFORNIA  LIBRARY 

BERKELEY 

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